You chose (b) ahead of (c) because you wanted to preserve coordination - is that right?
This is not the only reason. Except for predication, I consider all other modifications(for exx.. adjective) a sort of subordination. The original sentence has no tinge of "purpose", "result", or "cause"(look at "and that"). "attempts to move", "chance to win", or "need to call" are all kinda non-finite appositive clauses, or whatever you call/analyze, but not purposives.
If you chose purposive/result/cause, you are overreaching. We are asked not to change the original structure/meaning unless you find all ther choices are wrong/incoherent in many other ways.
The other way is to look at the scope of "that treat". In the original it is linked to "efforts", but not to the predicator.
In OG, there are examples re: chosing b/w subordination and coordination( the sloth, OG#163).