Botanists recognize over ﬁfty different species of sunﬂower. One species, the silverleaf sunﬂower, ______ both an early-
ﬂowering ecotype that tends to grow in coastal areas and a late-ﬂowering ecotype that grows inland.
having included
including
to include
includes
Choice D is the best answer. This verb needs to function as the main verb in the sentence, with the subject “one species,” so
it needs to be conjugated. This choice gives us the singular present tense “includes,” which is the only conjugated form of
the verb among the choices. 
Choice A is incorrect. This doesn’t complete the text in a way that conforms to the conventions of Standard English. This
verb needs to function as the main verb in the sentence, with the subject “one species,” so it needs to be conjugated. “Having
included” is a participle form of the verb: it’s not conjugated and doesn’t function like a normal verb. Choice B is incorrect.
This doesn’t complete the text in a way that conforms to the conventions of Standard English. This verb needs to function as
the main verb in the sentence, with the subject “one species,” so it needs to be conjugated. “Including” is the gerund form of
the verb: it’s not conjugated and doesn’t function like a normal verb. Choice C is incorrect. This doesn’t complete the text in a
way that conforms to the conventions of Standard English. This verb needs to function as the main verb in the sentence, with
the subject “one species,” so it needs to be conjugated. “To include” is the inﬁnitive form of the verb: it’s not conjugated.