The southern half of a certain region of the earth was covered entirely by water during the Cretaceous period, the last 75 million years of the Mesozoic era, the era when dinosaurs roamed the earth.
Statements
conditionals
Cretaceous → southern half of certain region period covered entirely by water
Dinosaur → lived on land
Dinosaur → didn't live through entire M era
facts
The C Period was the last 75 million years of the M era, when dinosaurs were alive. Plesiosaurs were not dinosaurs; they were swimming reptiles that lived exclusively during C Period.
Evaluate
Correct answers on Must Be False either contradict a conditional that was provided or contradict a Must Be True inference we can make from the info provided.
The conditionals don't seem to chain together, but we can apply them to some of the facts we got.
Plesio's lived exclusively during the C period, so we know that for the whole time Plesio's lived, the southern half of a certain region of earth was covered by water. We know that dinosaurs also lived during this time, but they lived only on land.
So .... Plesio's and Dino's couldn't have hung out much. Plesio's were swimming; they may have been in the underwater part of earth. Dinos were strictly on land.
How can we use the final sentence, that no Dino lived through the whole M era? I guess we could say that for the whole time dinos were alive, the southern half was covered by water.
Goal
There are too many possible inferences here to home in on one likely contender, so we'll have to be flexible.
We're not looking to pick an answer that represents a bad inference. We don't want Can't Prove That. We're looking to pick an answer we can actively contradict. We want Can Disprove That.