OG详解-OG3 文法 Q17

Choice C is the best answer. The convention being tested is subject-verb agreement. The singular verb “outlines” agrees in number with the singular subject “document.” 
Choice A is incorrect because the plural verb “have outlined” doesn’t agree in number with the singular subject “document.” Choice B is incorrect because the plural verb “were outlining” doesn’t agree in number with the singular subject “document.” Choice D is incorrect because the plural verb “outline” doesn’t agree in number with the singular subject “document.”