William Stern, a German psychologist, is widely recognized for introducing the concept of the Intelligence Quotient (IQ) in 1912. He proposed the ratio of mental age to chronological age as a way to quantify intelligence. While Alfred Binet developed the first practical intelligence tests, it was Stern who formalized the mathematical expression that became the standard for IQ measurement for many decades.

The formula for IQ is (Mental Age / Chronological Age) * 100. Given a mental age of 12 and a chronological age of 10, the calculation is (12 / 10) * 100, which equals 120. Note: The provided answer key lists 100, which is mathematically incorrect based on the standard formula. This discrepancy suggests a potential error in the source material provided for this question.

Individual differences are largely attributed to genetic influence, or heredity. This refers to the unique genetic material inherited from parents, which dictates physical traits, predispositions, and potential capabilities. While environment plays a role in development, genetics provide the foundational blueprint that distinguishes one individual from another in terms of biological and psychological characteristics.

Openness to experience is one of the 'Big Five' personality traits. Individuals who score high in this trait are characterized by their intellectual curiosity, appreciation for art, and willingness to try new things. They are generally more flexible in their thinking and are comfortable with change. In the context of sports and physical education, individuals with high openness may be more willing to experiment with new training methods, tactical strategies, and diverse physical activities.

Personality refers to the enduring set of traits and characteristics that influence an individual's cognition, motivation, and behavior across various situations. In sports psychology, understanding an athlete's personality helps in predicting how they might react to competitive pressure, interact with teammates, and respond to coaching styles. Although the term 'personally' is used in the option, it is intended to represent the concept of personality traits.

Social physique anxiety is a psychological construct describing the distress or apprehension an individual feels when they believe their body is being evaluated by others. It is deeply connected to self-concept, as it reflects how a person internalizes perceived social judgments about their physical appearance, often influencing their participation in physical activities.

In psychological theory, introversion is characterized by a tendency to direct energy and focus inward toward one's own thoughts, feelings, and internal experiences. Unlike extroverts, who gain energy from external social interactions, introverts often find social stimulation draining and prefer solitary activities or deep reflection. This internal orientation is a core personality trait that influences how individuals process information, interact with others, and manage their energy levels in various environments.

Childhood is defined as the developmental stage that follows infancy and precedes adolescence. It typically encompasses the years from birth up to approximately eight years old. This critical period is characterized by rapid physical growth, significant cognitive development, and the acquisition of essential social and emotional skills, forming the foundation for future development throughout the lifespan of an individual.

Motor skills, such as those required for cycling, swimming, or playing sports, are primarily acquired through consistent and repeated practice. Practice allows the nervous system to refine neural pathways, leading to improved muscle memory and coordination. While observation and imitation are helpful for initial learning, it is the actual physical repetition of the movement that solidifies the skill and enhances performance accuracy over time.

Behavior modification is a therapeutic approach based on learning theory, specifically operant and classical conditioning. It utilizes techniques such as stimulus control, reinforcement, and punishment to change maladaptive behaviors. Because it is a foundational technique in psychotherapy and relies heavily on managing environmental stimuli to influence behavior, both options A and B are correct.