I think this is a poor question, because all 4 choices are at least plausible.
"My good friend Ben is very poor and he never saves money."
If the speaker is discussing which of his friends save money and which don't, this would be an entirely plausible sentence. Like, "Al doesn't save money because he is wasteful and irresponsible. Carla is very frugal and is very good about saving money. Ben is very poor and he never saves money." Etc.
"spends" Well of course if he is any money at all he presumably spends some of it somewhere along the line. But you might say he "never spends money" as a poetic exaggeration, meaning that he rarely spends money or he never spends money unnecessarily. This is a fairly unlikely thing to say but plausible.
"wastes" Sure, this makes sense. Some poor people waste what little they have, so the statement is not obvious or redundant. Some people are poor BECAUSE they waste money.
"costs" Unlikely but possible in the right context. Like, "Wow, Al always costs me money. He's poor and so he's always borrowing from me. Ben is poor but he doesn't cost me anything." "costs" would also be unlikely if you didn't say who he imposes costs on, like "costs me money" or "costs his parents money".
So I could see if they said D is incorrect. A and C are both completely plausible, and B is unlikely but reasonably possible.
Yes, "and" is generally used when the second thought logically follows from the first, or goes along with the first. That would make "costs" unlikely, but doesn't really subtract from any of the other three.