In paleontology, the term “Elvis taxon” gets applied to a newly identiﬁed living species that was once presumed to be extinct.
Like an Elvis impersonator who might bear a striking resemblance to the late musical icon Elvis Presley himself, an Elvis
taxon is not the real thing, ______ is a misidentiﬁed look-alike.
however but it
however it
however, it
however. It
Choice D is the best answer. The clause “Like an Elvis impersonator…real thing” and the clause “it is…look-alike” are both
independent clauses, so making them into two separate sentences is grammatically correct. 
Choice A is incorrect. This choice creates a run-on sentence error. The clause “Like an Elvis impersonator…real thing” and the
clause “it is…look-alike” are both independent clauses, so they need to be separated with at least a comma + a coordinating
conjunction. This choice provides the coordinating conjunction “but,” but it’s missing a comma. Choice B is incorrect. This
choice creates a run-on sentence error. The clause “Like an Elvis impersonator…real thing” and the clause “it is…look-alike”
are both independent clauses, so they need to be separated with a semicolon, a colon, a dash, a period, or a comma + a
coordinating conjunction. Choice C is incorrect. This choice creates a run-on sentence error. The clause “Like an Elvis
impersonator…real thing” and the clause “it is…look-alike” are both independent clauses, so they need to be separated with at
least a comma + a coordinating conjunction. This choice provides a comma, but it’s missing a coordinating conjunction.