Question

why must the misuse of prescription and illegal drugs be avoided?
o reduces the risk of serious side effects
o decreases blood pressure
o reduces respiratory diseases
o decreases the risk of cancer

Explanation:

Misusing prescription or illegal drugs can lead to serious side - effects like organ damage, addiction, etc. The other options are not the main reasons directly related to drug misuse. Reducing the risk of serious side - effects is the most relevant reason among the given ones.

Answer:

reduces the risk of serious side effects