The
notionthat our happiness or our suffering depend upon ourselves
is not always true.
The subject, notion, is singular. If you have doubts you can look at the verb "is". That being said we need to use "depends". Eliminate A, C, and D. (A) our suffering depend upon ourselves(B) our suffering depends upon us
(C) our sufferings depend upon ourselves(D) our suffering depend on us(E) our suffering depends upon ourselves
To difference between B and E is the last word. It's between "us" or "ourselves". Does our happiness and suffering depend on us, as in you and me? No. Happiness and suffering depends on the individual. Strike out B. The answer is E.