Physics question on identify the reaction?

Question

I am having trouble with the question a, b, and c in this physics problem:

One or more external forces are exerted on each object enclosed in a dashed box shown in the figure below. Identify the reaction to each of these forces. (Assume that (a), (b) and (c) occur on Earth while (c), (d) and (e) occur far from any outside gravitational influences. Select all that apply.)

The pictures for a, b, c are here:
yuer365.info/pictures/4%20Diagram…

Here are my selected answers (but they are incorrect... I don't know if I am missing of the choices or what... )
yuer365.info/pictures/4%20QA.jpg
yuer365.info/pictures/4%20QB.jpg
yuer365.info/pictures/4%20QC.jpg

Please help. Thank you in advance.

Answer 1

The first one is the diagram, the image is
yuer365.info/pictures/4 Diagram.jpg

Sorry that I have to post image as the question is based on the diagram.

Thank you!