Inhospitable places on our planet, from steaming hot springs to the thick ice of the polar regions, tend to be populated by specially adapted microbes flourishing, it seems, in these extreme conditions and are therefore called "extremophiles."
Test Points: Scentence structure & Parallelism
(A) flourishing, it seems, in these extreme conditions and are (
this scentence is a frament, the structure is awkward)
(B) that seem to flourish with these extreme conditions and (
"with" is not idiomatic; "seem to flourish..." and " are therefore called" constitutes active+and+passive structure which violates parallelism)
(C) that seem to flourish in these extreme conditions and that are
(D) seeming to flourish in these extreme conditions and are (
same reason as choice B)
(E) seeming to flourish with these extreme conditions and that are (
"seeming to flourish..." and " that are therefore called" violates parallelism)