practicing space walking counseling activities for tension exercising to maintain strength monitoring circadian rhythms
I gave my students this multiple choice question: Scientists noted that muscles and bones would need physical stress to remain healthy during manned space flights. Which of these had to be planned for because of this need?

Only one answer is correct among these 4 choices:
- practicing space walking
- counseling activities for tension
- exercising to maintain strength
- monitoring circadian rhythms

Could you tell me which one is correct?

exercising to maintain strength