Answer: A. When is creating a new vaccine appropriate?
D. How did the hole in the ozone layer form?
Step-by-step 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.