Why is A incorrect?

Can you please tell me why A is not correct?

@Jamiee-Salgado Here, we're concerned about the tagged armadillos, not the untagged ones. This means that it doesn't matter much how many were able to avoid being tagged. What we're concerned about is how quickly they move. E works here because if the researcher believes they didn't stray far from where they started, they have to believe that the armadillos didn't migrate for winter and simply come back to where they started.