answer:The analysis…must be simplified to obtain… Both of the other ones sound a bit awkward to me, the second one moreso than the first. “Making simplifications” is something that you, the scientist, are doing, but the second sentence implies that the analysis is doing it, which doesn’t really make sense. The first one makes sense, I think, but sounds a bit awkward to me. Mostly because “made” is not really a verb that makes sense for an analysis, I think.