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.

I thinkyour answer is it.

Explanation:

Answer chocices

Group of answer choices

No unclear antecedents

Their

It

Them

can you type the questions out? we cant really see anything

the legal limit for the drivers who can drive after consuming any amount of alcohol is 21 years.

explanation:

on november 1, 1996, a "zero tolerance law" was put into effect in the new york state.

according to this zero tolerance law, for people under the age of 21 years, it was illegal to purchase and possess alcohol or to drive after consuming any amount of it.

also, the alcohol involvement rate for the drivers under the age of 21 was roughly twice that of elderly drivers.