motor skills deficits in the left side of the body
Explanation:
The frontal lobe is a part of the cerebral cortex of the brain.
The frontal lobe is involved in performing several functions in the body which include motor function, spontaneity, memory, language, movement control, etc.
Since in the given question it is given that Kelsey has a tumor in the right frontal cortex, the symptom that might have prompted the scan to take place must be motor skills deficiency in the left side of the body as the right side controls the left side.