Which choice completes the text so that it conforms to the conventions of Standard English?
A
their
B
they’re
C
its
D
it’s
Explanation
Correct answer: C.
Choice C is the best answer. The convention being tested is the use of possessive determiners. The singular possessive determiner "its" agrees in number with the singular subject "the Tajik Republic" and thus indicates that the other republics were its peers.
Why the other choices are wrong
Choice A
Choice A is incorrect because the plural possessive determiner "their" doesn’t agree in number with the singular subject "the Tajik Republic."
Choice B
Choice B is incorrect because "they’re" is the contraction for "they are," not a possessive determiner.
Choice D
Choice D is incorrect because "it’s" is the contraction for "it is" or "it has," not a possessive determiner.