choose and write the letter of the correct answers in your answer sheet

It's on the pic

this is the other one,
5.the following are effects in the environment by the changes in matter. Which of these has a good effect on the environment ?
a. air pollution
b. composting
c. deforestation
d. water pollution
6.many families use wood as fuel in cooking food ,What is the bad effect on the environment of this activity ?
a. deforestation
b. air pollution
c. land pollution
d. water pollution ​