Not only did the students include full sentences from the source without using quotation marks, but they also fail to properly cite paraphrased material.

In the original sentence, there was a tense inconsistency between the verbs "include" and "fail." The verb "include" is in the past tense, while the verb "fail" is in the present tense, creating confusion about the timing of these actions.

To correct the sentence, we must ensure that the verbs are in the same past or present tense, depending on the context. Since the sentence refers to actions that have already happened, we must use the past tense for both verbs. Therefore, the present tense "fail" should be changed to the past tense "failed," creating tense consistency in the sentence.

Correct sentence: "Not only did the students include full sentences from the source without using quotation marks, but they also failed to properly cite paraphrased material."

The answer is option B.