Which diagram below best represents the chromatids if only crossing-over has occurred?

I’m doing some practice exam questions for biology, and i’m not sure how to do these 3 parts to the question.

What molecule does hemoglobin decay into over time

Anurse is caring for a client who is learning how to take care of a newly created colostomy. when observing a return demonstration of the colostomy irrigation, the nurse evaluates that more teaching is required when the client carries out what procedure?