I have committed to crossing my legs I hope carefully, ankle on knee, hands together in the lap of my slacks. My fingers are mated into a mirrored series of what manifests, to me, as the letter X. The interview room’s other personnel include: the University’s Director of Composition, its varsity tennis coach, and Academy prorector Mr. A. deLint. C. T. is beside me; the others sit, stand and stand, respectively, at the periphery of my focus. The tennis coach jingles pocket-change.

Based on this excerpt, which detail is implicit?
More chairs are needed to make seating available for all attendees.
Hal is sitting in a chair with his ankle on his knee.
The Director of Composition is involved in the interview process.
The tennis coach has money in his front pocket.

More chairs are needed to make seating available for all attendees.

Explanation:

To make an implicit meaning is to say about something but not mentioned or expressed directly. It may be stated in some way but not directly mentioned.

In the given excerpt from Infinite Jest by David Foster Wallace, the narrator talks about the interview room that he was seated in. The only implicit detail he furnished was that the room needs more chairs for others to be seated. This is seen in the passage "the others sit, stand and stand", while the other options are clearly stated.  

Hal seated in a chair with his ankle on his knee ("ankle on knee, hands together in the lap of my slacks"), the Director of Composition involved in the interview process ("interview room’s other personnel include: the University’s Director of Composition") and the tennis coach with money in his pocket ("jingles pocket-change") are all stated explicitly.

Thus, the correct answer is the first option.