Which of the following questions can use science as a method of inquiry?

a. when is creating a new vaccine appropriate?

b. is country music the best or the worst type of music?

c. do ghosts exist?

d. how did the hole in the ozone layer form?

A. When is creating a new vaccine appropriate?

D. How did the hole in the ozone layer form?

Explanation:

Science can answer questions or inquiry by utilizing suitable experimental methodology or by direct observation on something which can prove a reason for the cause of a natural phenomena.

Among the options given A. When is creating a new vaccine appropriate? and D. How did the hole in the ozone layer form? are correct. As these involves both experimental and observatory study to be answered.