Darwin and wallace's theory of evolution by natural selection was revolutionary because it

Notice a couple of things different between (A) and (B). It was NOT the first time a biologist proposed that species changed through time (so it's not B). But it finally *solidified* that idea by giving "change through time" (evolution) a MECHANISM. It gave a plausible explanation for WHY species change over time, in a testable way that made sense and had evidence to support it.

So it finally dismissed the idea that species are constant.

It also emphasized that the simple presence of *variation* within a population was a key reason for evolution.

While we're at it ... (C) is wrong because it's not *individuals* that acclimate (adapt) to their environment, but the population (the species) as a whole.

And (D) is wrong because it had nothing to do with economics or the monarchy.