Choose the word (a, b, c, or d) that best fits each of the blank space

Choose the word (a, b, c, or d) that best fits each of the blank spaces.  Hoa is excited about the (Question 21) ___ activities she is going to do. The Y&Y is having a plan (Question 22) ____ the community. She’ll (Question 23) ____ in its recycling program. In joining this program, she’ll collect (Question 24) __ paper, glass and empty cans. Then she will send them for (Question 25)___. She hopes that she could save natural resources and earn some money for her school Y&Y in these (Question 26)___. She also thinks about participating in (Question 27) ____ planting trees and flowers or (Question 28) ____ the street children. Question 21.