In this question, we want to know if the deadline for a response falls on a Friday, and we know the 84 hour limit, so we are going to need some information about when the inquiry was placed. On to the statements, separately first.
Statement (1) tells us that the inquiry was placed on a Tuesday. 84 hours is 3.5 days. If the inquiry came Tuesday at 8am, the last moment for a reply would be Friday at 8pm. But if the inquiry came Tuesday at 8pm, the last moment for a reply would be Saturday morning at 8am. As we can't make a single definitive answer to the question, Statement (1) is insufficient.
Statement (2), alone, doesn't tell us which day we are talking about! If the inquiry could happen at 3:00 pm Tuesday and be due 3:00 am Saturday morning; or it could happen Monday at 3:00 pm and be due on Friday. Insufficient.
When the statements are combined, the range of possibilities has been narrowed to Tuesday from 2:00 pm to 4:00 pm. The corresponding range of possible deadline times is on Saturday from 2:00 am to 4:00 am. The answer to the question for this entire range of possibilities is "no," so we are able to answer the question definitively. The statements are sufficient together.
The correct answer is (C).