What were the buffalo soldiers function on the frontier?

The graph shows the price of a good compared to the quantity demanded and the quantity supplied. on this graph, the bottom horizontal line represents an ineffective price floor set above equilibrium. an effective price floor set below equilibrium. an ineffective price ceiling set above equilibrium. an effective price ceiling set below equilibrium.

Doing the text now can someone me

Which pronoun has an unclear antecedent in the following sentences? the sixth-grade students liked volunteering their time to read to the elderly people in the hospital. it made them happy. a. their b. it c. them d. no unclear antecedents