Why did civilization start in river valleys

Read the excerpt from david foster wallace’s infinite jest. 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? a.  more chairs are needed to make seating available for all attendees.b.  hal is sitting in a chair with his ankle on his knee.c.  the director of composition is involved in the interview process.d.  the tennis coach has money in his front pocket.