Explanation
Correct answer: D.
Choice D is the best answer. "However" logically signals that the claim in this sentence—that many New Yorkers have seen Pollard’s work in a famous Broadway musical—is true despite the previous information that few New Yorkers have heard Pollard’s name.
Why the other choices are wrong
Choice A
Choice A is incorrect because "similarly" illogically signals that the claim in this sentence is similar to the previous information that few New Yorkers have heard Pollard’s name. Instead, the claim that many New Yorkers have seen Pollard’s work is true despite the previous information.
Choice B
Choice B is incorrect because "therefore" illogically signals that the claim in this sentence is a result of the previous information that few New Yorkers have heard Pollard’s name. Instead, the claim that many New Yorkers have seen Pollard’s work is true despite the previous information.
Choice C
Choice C is incorrect because "for example" illogically signals that the claim in this sentence exemplifies the previous information that few New Yorkers have heard Pollard’s name. Instead, the claim that many New Yorkers have seen Pollard’s work is true despite the previous information.