Explanation
Correct answer: C.
Choice C is the best answer. "However" logically signals that the claim in this sentence—that the weight of the gold rhinestones likely limited Elvis’s mobility—contrasts with the previous information about the material being flexible enough for Elvis’s dance moves.
Why the other choices are wrong
Choice A
Choice A is incorrect because "for this reason" illogically signals that the claim in this sentence is caused by the previous information about the material being flexible enough for Elvis’s dance moves. Instead, the claim that the weight of the suit’s rhinestones limited movement contrasts with the previous information about the jumpsuit’s flexibility.
Choice B
Choice B is incorrect because "firstly" illogically signals that the claim in this sentence is the first in a series of claims about the jumpsuit being flexible enough for Elvis’s dance moves. Instead, the claim that the weight of the suit’s rhinestones limited movement contrasts with the previous information about the jumpsuit’s flexibility.
Choice D
Choice D is incorrect because "in other words" illogically signals that the claim in this sentence is a paraphrase or restatement of the previous information about the material being flexible enough for Elvis’s dance moves. Instead, the claim that the weight of the suit’s rhinestones limited movement contrasts with the previous information about the jumpsuit’s flexibility.