Final answer:
Terrance's reaction time will increase because he needs to adapt to the cursor moving in the opposite direction, which requires additional mental effort and time.
Step-by-step explanation:
The question asks about the effect of a computer virus on Terrance's reaction time when his mouse cursor moves in the opposite direction. The correct answer is (a) Terrance's reaction time will increase; because he has to adjust to the inverted cursor. When a cursor moves inversely to the mouse's movements, it can be disorienting and requires mental recalibration, which takes additional time, leading to an increased reaction time.