To answer this question, let's analyze each option:
Option A) "Six months? Don't you really mean twelve?" - This option is incorrect because it assumes that the speaker made a mistake in estimating the time required for the project and suggests that it should take longer.
Option B) "We're not busy. Our department could do it in less time than that." - This option is incorrect because it contradicts the statement made in the comment about how busy they are. It suggests that the department is not busy and can complete the project in a shorter time.
Option C) "You always say that." - This option is incorrect because it does not address the issue of the project requiring six months to complete or the speaker's statement about being busy during this time of year.
Option D) "What characteristics of the project require six months? Sounds like you're busy! What are some of the other projects you're handling?" - This option is correct because it acknowledges the statement made about the project requiring six months to complete and the speaker's comment about being busy. It seeks more information about the project's characteristics and other projects the speaker is handling.
Therefore, the correct answer is D) "What characteristics of the project require six months? Sounds like you're busy! What are some of the other projects you're handling?"