We can see here that some observations did something to the Ptolemaic theory - they could either confirm it or discredit it. Those observations led to something that happened to scientists' views - we can sense that it had to change them in some way.

Words that could potentially fit the first blank are choice (A), "proved," (B), "invalidated," and (D), "corroborated." "Invalidate" means "to deny validity," and "corroborate" means "to support with evidence." Each of those words could fill the first blank, so we need to look for the second word. In (D) we have "rebirth," and we wouldn't say "rebirth in," but rather "rebirth of," so we can deem that option incorrect. We are left with choice (A), "reversal," and choice (B), "shift." Since the Ptolemaic theory was "reigning," it was the current favorite at the time of the observation. Therefore, choice (A) doesn't make sense; if you prove the current theory, then there is no reversal.

The correct answer is (B).