"Dr. Smith had argued that the cure for insomnia could be found in the seeds of apples, and although it was not true, he had made money giving lectures." This statement:

*** includes a shift in tense.

is a sentence fragment.

includes an inappropriate use of a comma.

includes a shift in person.

includes a pronoun with no appropriate antecedent.

Correct.

The correct answer is: "includes a shift in tense."

To identify this answer, we need to understand what tense refers to. Tense is the form of a verb that shows when an action takes place. In the given statement, we can see a shift in tense where the past tense "had argued" is followed by the present tense "could be found." This shift indicates that the actions or events are not happening simultaneously but are being expressed in different time frames.

So, the correct answer is that the statement includes a shift in tense.