"Stand Up Straight, Mom," a Young Woman Said to an Older

"Stand up straight, mom," a young woman said to an older woman in the grocery store checkout line. Which of the following would be the most appropriate action by the nurse who is standing next to them in line?

A) Do nothing; the nurse is not expected to act as a nurse when not at work.
B) Say to the older woman, "You need to start treating that osteoporosis."
C) Say, "Older women who don't get much calcium, vitamin D, or exercise can often have trouble standing up straight. Keep reminding yourselves."
D) Say, "You both may have some problems. Have you both ever been checked for osteoporosis?"