Can someone help me out with this? I tried a-lot of combinations to see which one it would logically be, but I'm stuck as of this moment.
C. The last box in a row contains the elements that the previous two boxes have in common.
The answer is C. The puzzle would make more sense if the puzzle had consistent factors both vertically and horizontally (instead of just horizontally). Edit2: Nope. It's not all one puzzle. It's two examples followed by a puzzle. Whoever made this doesn't understand the benefits of spacing.
Edit1: Oh, I'm being downvoted! Thanks for the warm Stack-exchange welcome!
Anyway, boboquack wants me to update my answer. so here you go: It appears that there are at least two potentially consistent factors per horizontal row. This rules out B and D. None of the factors that have been removed from previous panels in the first two rows were added back in later panels on the same row. Therefore A doesn't seem logically consistent with the rest of the puzzle. With so little information that's more of an assumption than a provable trend, but it's enough information to make C a more likely answer, as there's no potential reason for it not to be.
Though, in hindsight, it appears that my method for solving this puzzle is a bit more... roundabout than Johnmark Perry's. (I clearly made this puzzle into something more complicated than it is after overlooking something simple; I initially mistook this for a grid puzzle rather than three different examples, and approached it as such. Some spacing would make the puzzle more clear, honestly)