<span>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.</span>
The answer is A. Habitat !
Fimbriae, flagella and pili are all examples of blank structures found in some bacteria.
