The first cause you would think of if there is a change in mental status in an older adult, particularly confusion, is:

A primary cause of change in mental status, particularly confusion, in older adults is drug toxicity.

Drug toxicity occurs when a person has accumulated too much of a drug in their bloodstream which results into  adverse effects on the body.

answer; ///he could not explain why the continents drifted;

answer; /// the above statement is (true);