OG详解-OG3 文法 Q21

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