SAT Question 2784cbaf: Form Structure And Sense answer and explanation

Choice A is incorrect because the context requires the plural noun "variables," not the singular possessive noun "variable’s."

Choice C is incorrect because the singular count noun "object" needs a determiner in this construction, as in "an object’s movement" or "the object’s movement." This choice instead produces "variables that characterize object’s movement," which lacks that determiner. The earlier "an" modifies the earlier occurrence of "object" and does not carry over to this phrase. Choice B correctly uses the plural possessive "objects’" to discuss objects in general without an article. The number of variables does not determine whether the object is singular or plural.

Choice D is incorrect because the context requires the plural possessive noun "objects’," not the plural noun "objects."