Rust can deteriorate a steel pipe to such an extent that it will snap easily, as though it was a twig
Answers
The expression “as though” introduces a supposition that is contrary to fact (the pipe is not a twig). Such suppositions must be expressed in the subjunctive mood. For example, in the phrase "I wish I were rich," the verb "were" is in the subjunctive because the phrase expresses a desire contrary to fact. The appropriate singular form of the verb “to be” in the subjunctive mood is “were.”
(A) This choice is incorrect as it repeats the original sentence.
(B) “Like” should not be used to introduce the comparative clause “a twig does.” The word “as” should be used instead. "Like" is used to compare nouns only.
(C) The verb “is” is not appropriate for the subjunctive mood. The appropriate singular form of the verb “to be” in the subjunctive mood is “were.”
(D) The verb “was” is not appropriate for the subjunctive mood. The appropriate singular form of the verb “to be” in the subjunctive mood is “were.” In addition, this choice changes the meaning of the sentence. While the original sentence asserts that it is possible for rust to deteriorate a steel pipe to the point where it will snap easily, this choice asserts only that it is possible for rust to deteriorate the pipe to a point where it might snap, i.e., it implies a somewhat lesser degree of possible deterioration.
(E) CORRECT. This choice correctly uses the subjunctive “were.”