Step 1: Understanding the Question
The question asks for the Latin legal maxim that translates to "Let the buyer beware". This principle places the responsibility on the buyer to perform due diligence before making a purchase.
Step 2: Translating and Analyzing the Maxims
(A) Caveat emptor: This breaks down into \textit{Caveat} ("let him beware") and \textit{emptor} ("the buyer"). The full translation is "Let the buyer beware". This is the principle that the buyer alone is responsible for checking the quality and suitability of goods before a purchase is made.
(B) Caveat actor: This means "Let the doer beware". It implies that the person performing an act is responsible for its consequences.
(C) Caveat venditor: This means "Let the seller beware". This is the opposite principle to caveat emptor, placing a duty on the seller to disclose information about the goods.
(D) Persona non grata: This means "an unwelcome person". It is a term used in diplomacy for a foreign person whose entering or remaining in a certain country is prohibited by that country's government.
Step 3: Final Answer
The maxim that means "Let the buyer be beware" is Caveat emptor. Therefore, option (A) is the correct answer.