By choosing glass apartments towering a hundred feet over brownstone units designed for earlier generations, seemingly younger-than-ever moneyed professionals have embraced a modern design ethic that accentuated their luxury-laden lives.

A By choosing glass apartments towering a hundred feet over brownstone units designed for earlier generations, seemingly younger-than-ever moneyed professionals have embraced a modern design ethic that accentuated
B By choosing glass apartments towering a hundred feet over brownstone units designed for earlier generations, seeming younger-than-ever moneyed professionals have embraced a modern design ethic that accentuates
C In choosing glass apartments in hundred-foot towers instead of brownstone units designed for earlier generations, seemingly younger-than-ever moneyed professionals have embraced a modern design ethic that accentuates
D In choosing glass apartments in hundred-foot towers instead of brownstone units designed for earlier generations, seemingly younger-than-ever moneyed professionals have embraced a modern design ethic that accentuated
E In choosing glass apartments towering a hundred feet over brownstone units designed for earlier generations, seeming younger-than-ever moneyed professionals have embraced a modern design ethic, accentuating

Mt reasoning : Highlight to view
C is the right answer
A and D are gone because of accentuated (past tense)
B and E are gone because of the use of seeming.

Yep! You've got it. The past tense "accentuated" clashes with the present perfect "have embraced." Elim A and D. And "seeming / seemingly" is modifying the adjective "younger-than-ever" - adverbs have to modify adjectives, so we need the "seemingly" version of the word. Elim B and E. And you're done!

Bumping up the thread to understand whether the usage of 'instead of' is correct.
Please clarify. Thanks.

'instead of' here is ok, because it's used with a NOUN (instead of brownstone units...)
note that you could also use 'rather than' in the same context. ('rather than' is more general - it's acceptable with nouns, adjectives, verbs, ...just about anything - while 'instead of' is strictly limited to nouns and constructions that act as nouns.)

note that the use of 'over' here is unacceptable, because it creates as unintended interpretation: the glass apartments tower 100 feet over the brownstones (= they're standing next to each other, and the glass buildings are 100 feet taller). the use of 'instead of' results in a sentence free of ambiguity.