A model created by biologist Luis Valente predicts that the rate of speciation—the rate at which new species form—on an
isolated island located approximately 5,000 kilometers from the nearest mainland ______ triple the rate of speciation on an
island only 500 kilometers from the mainland.
being
to be
to have been
will be
Choice D is the best answer. The convention being tested is ﬁnite and nonﬁnite verb forms within a sentence. Relative
clauses, such as the one beginning with “that,” require a ﬁnite verb, a verb that can function as the main verb of a clause. This
choice correctly supplies the clause with the ﬁnite future tense verb “will be.” 
Choice A is incorrect because the nonﬁnite participle “being” doesn’t supply the clause with a ﬁnite verb. Choice B is
incorrect because the nonﬁnite to-inﬁnitive “to be” doesn’t supply the clause with a ﬁnite verb. Choice C is incorrect because
the nonﬁnite to-inﬁnitive “to have been” doesn’t supply the clause with a ﬁnite verb.