Which of the following diagnostics test is used to assess the function of the heart

So i have a lot of answers answered but it says i still need to answer more questions. why is it doing that? how many questions need to be answered?

What is the hormone in your brain that makes you feel happy?

Frankie is having difficulty developing a friendship with histeammate curtis. whenever frankie invites curtis to hangout with him at the park, curtis always says that he's busy.what is most likely preventing a healthy relationship fromforming? a)the boys are not being generous with their time andeffort.b)the boys are not communicating.c)both boys are too busy.d)the boys are on different teams.