what is the name of the class system that was very rigid and designated people's roles, jobs, and social standings in the Indus river valley civilization?

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.