So it's asking you to choose the word that is most likely to fit in the sentence based off of context clues.
1) is fundamentally because the wheel was a very important invention and changed the way humans used their surroundings
2) is really because her invention did help improve the quality of water
Continue on with this type of pattern. Keep in mind to look for extremes, like "absolutely", "completely", and "certainly". These words can change the meaning of a sentence by a lot.
