Answer the following question according to formal grammatical rules. What is the antecedent for the pronoun "It" in the following passage?

The sixth-grade students liked volunteering their time to read to the elderly people in the hospital. It made them happy.
Sixth-grade students
Volunteering
Time
Hospital

Volunteering

Explanation:

I hope this will help u dear

1. (1.2kw)x(15/60hours) = .3kwh --> a

2. (5kw)x(90/60hours)x(8cents/kwh) = $0.60 --> d

3. microwave --> 1200 watts = (1.2kw)x(6/60hours) = .12kwh

coffee-maker --> 900 watts = (.9kw)x(10/60hours) = .15kwh

therefore, it requires more energy for the coffee-maker to do the same amount of work.

so the answer is a.

meteorologists would compare a new weather map with one 24 h old to see how fast a front is moving.