British scientists James Watson and Francis Crick won the Nobel Prize in part for their 1953 paper announcing the double
helix structure of DNA, but it is misleading to say that Watson and Crick discovered the double helix. ______ ﬁndings were
based on a famous X-ray image of DNA ﬁbers, “Photo 51,” developed by X-ray crystallographer Rosalind Franklin and her
graduate student Raymond Gosling.
They’re
It’s
Their
Its
Choice C is the best answer. The convention being tested is the use of possessive determiners. The plural possessive
determiner “their” agrees in number with the plural conjoined noun phrase “Watson and Crick” and thus indicates that the
ﬁndings were those of Watson and Crick.
Choice A is incorrect because “they’re” is the contraction for “they are,” not a possessive determiner. Choice B is incorrect
because “it’s” is the contraction for “it is” or “it has,” not a possessive determiner. Choice D is incorrect because the singular
possessive determiner “its” doesn’t agree in number with the plural conjoined noun phrase “Watson and Crick.”