A cost that exhibits characteristics of both fixed and variable costs is commonly referred to as either a mixed cost or a semi-variable cost. These costs remain constant up to a certain level of activity (fixed portion) and then increase in proportion to changes in activity levels (variable portion). Since both terms are standard accounting nomenclature for the same concept, both options B and C are correct.

To find the total number of units sold across a product line, one must aggregate the individual sales volumes of each product. By summing the units for Product A (200), Product B (300), and Product C (400), we arrive at a total of 900 units. This calculation is a basic step in analyzing sales mix and overall market demand for a company's diverse product offerings.

The sales mix variance measures the impact of changes in the proportion of products sold compared to the original budget. It is calculated as the difference between the actual sales mix contribution margin and the budgeted sales mix contribution margin. This metric helps management understand how shifts in product popularity affect total profitability, allowing for better strategic adjustments in marketing and pricing to optimize the overall sales portfolio.

The Theory of Constraints (TOC) is a management philosophy that views any system as being limited in achieving more of its goals by a very small number of constraints. By identifying these bottlenecks and focusing efforts on optimizing them, organizations can improve throughput and maximize overall income. It emphasizes that non-bottleneck resources should be managed to support the capacity of the bottleneck.

The contribution margin percentage, also known as the contribution margin ratio, represents the percentage of each sales dollar that remains after covering variable costs. It is calculated by dividing the contribution margin per unit by the selling price. This ratio is a critical tool for management to assess the profitability of products and to perform break-even and target profit analysis.

When the amount of overhead applied to production ($2,000) is less than the actual overhead costs incurred ($2,200), the overhead is considered under-allocated. However, the provided answer key labels this as 'over allocated budget'. In standard accounting terminology, this is an under-allocation variance. We retain the provided answer key while noting the discrepancy in standard terminology.

Costs of quality include expenses associated with preventing defects, identifying and correcting errors, and dealing with the consequences of product failures. This encompasses various activities like quality control, training, and warranty claims. By investing in prevention and appraisal, companies aim to reduce the costs of internal and external failures, ultimately improving product reliability and customer satisfaction while minimizing waste and rework expenses throughout the production process.

Facility-sustaining costs represent the expenses required to maintain the organization's infrastructure, such as factory rent, plant management salaries, and general security. These costs benefit the entire facility rather than any single product or service. Because they do not have a clear cause-and-effect relationship with specific production activities, they are often allocated using broad, arbitrary bases or treated as period costs.

The slope coefficient in a cost function represents the variable cost per unit of activity (in this case, machine hours). To determine the change in activity, we divide the total change in cost by the variable cost per unit. Thus, $16,000 divided by 0.40 equals 40,000 machine hours. This calculation is fundamental for understanding cost-volume relationships.

A labor price variance is unfavorable when the actual cost of labor exceeds the budgeted or standard cost. In this case, the actual payment of $1,200 is higher than the budgeted amount of $1,000, indicating that the company spent more than planned for labor services. This negative variance suggests either higher wage rates than anticipated or inefficiencies in labor utilization that resulted in increased costs.