If older adults are at risk of falling, they should do exercises that maintain or improve a. flexibility b. muscle strength c. balance d. both b and c

The answer is B, the muscle strength helps stability.

I would say D both b and c would help you from falling, balance will help you keep steady so you don't fall and muscle would improve your strength of holding on to that balance making it harder for you to fall over. flexibility just makes you flexible it doesn't help your balance