The answer is B. Although it may seem the other answers are correct as well, in fact they are not. A 'complex paragraph' is indeed one which explains multiple sides of an issue, but favors one, thus only one main topic is represented. It doesn't really matter where the topic sentence is placed - it can be anywhere in the paragraph. However, it is traditionally placed in the first sentence, although that rule isn't written in stone - the topic sentence can also be placed at the end of the paragraph. Therefore, we are left with only one option, and that is B, 'a paragraph should have one main topic'.
C does not have a wife , is correct I think i tried my best to figure it out
