TPR FL 2 Bio section

I am quite confused about #36. For choice B it talks about fluid retention in the lower extremities. Why would this occur?

Also, how does being in recumbent position affect shortness of breath in general? I guess I don't understand 36 in general.

For #40, why would tropomyosin be in serum? I thought it was something that is attached to actin of muscle cells?


Answers are D for both 36 and 40.


Thank you!