Final answer:
Keys should generally be returned immediately after showings to maintain security and accountability, although the correct answer may vary depending on specific office policies or local regulations.
Step-by-step explanation:
The question refers to the standard practice in real estate for returning keys to the office after property showings. While the exact timeline can depend on the real estate company's policy or local regulations, a professional standard is typically to return keys as soon as possible to ensure security and readiness for the next showing. Unless otherwise specified by the office policy, option A) Immediately is often considered best practice to maintain security and accountability. However, without explicit instructions from the office or in the policy document, it's not possible to determine a universally correct answer to this question.