The phrase 'Tête-à-tête' is of French origin, literally translating to 'head-to-head'. In English usage, it refers to a private, intimate conversation between two people, typically held in person. Therefore, 'face to face' is the correct definition for this idiom.

The term 'viz' is an abbreviation of the Latin 'videlicet', which translates to 'that is to say' or 'namely'. It is commonly used in formal writing to introduce a clarification or a list of items.

The Latin legal term 'Ipso jure' translates directly to 'by the law itself' or 'by operation of law'. It is frequently used in legal contexts to describe a situation where a legal consequence follows automatically from the law without the need for any specific action, court order, or intervention by the parties involved.

The phrase 'en route' is borrowed from French and is commonly used in English to describe someone or something that is currently in the process of traveling or moving toward a specific destination. It literally translates to 'on the way' and is used to indicate that a journey is currently underway.

The term 'de facto' is a Latin expression that translates to 'in fact' or 'in reality'. It is commonly used to describe a state of affairs that exists in practice, even if it is not officially or legally recognized.

The Latin phrase 'Pro bono publico' is a common legal and professional term. It translates directly to 'for the public good'. It is frequently used to describe professional work, especially legal services, performed voluntarily and without payment as a public service.

The legal term 'Ex post facto' is derived from Latin and translates to 'from a thing done afterward'. It refers to laws or actions that have a retroactive effect, meaning they apply to events that occurred before the law was enacted.

The term 'Ex-parte' is a Latin phrase frequently used in legal contexts. It refers to a proceeding, order, or motion brought by or for one party only, without notice to or challenge by the other side. Therefore, it signifies an action taken from or on behalf of one side only.

The Latin phrase 'Ultima ratio' translates literally to 'the last argument' or 'the final argument'. In political and military contexts, it is often used to describe a last resort or the final means of settling a dispute when all other diplomatic or peaceful options have been exhausted.

The Latin term 'vide supra' is commonly used in academic and legal writing to direct the reader to information previously mentioned in the text. It translates directly to 'see above'. Conversely, 'vide infra' would mean 'see below'. Therefore, option B is the correct translation for this specific phrase.