What is true about A/B testing? (Choose two answers)

What is true about A/B testing? (Choose two answers)
A . You can disable A/B testing before and after email sent.
B . You can only do A/B testing on list emails.
C . When you turn off A/B testing you will have to choose which version to keep.
D . It is recommended to test at least 5 different elements in your A/B tests.

Answer: B,C