OG详解-OG1 文法 Q16

Choice C is the best answer. The convention being tested is subject-verb agreement. The singular verb “has been” agrees in number with the singular subject “writing.”
Choice A is incorrect because the plural verb “were” doesn’t agree in number with the singular subject “writing.” Choice B is incorrect because the plural verb “have been” doesn’t agree in number with the singular subject “writing.” Choice D is incorrect because the plural verb “are” doesn’t agree in number with the singular subject “writing.”