Final answer:
The incorrect word in the sentence is 'whose,' which should be 'who's,' a contraction for 'who has.' The sentence incorrectly suggests possession when it needs to convey the meaning of 'who has.'
Step-by-step explanation:
The word used incorrectly in the sentence is 'whose.' It should be replaced with 'who's,' which is the contraction for 'who has.' The corrected sentence should read: I was surprised to learn that Mark Gomez who's given hundreds of presentations at conferences and university events is terrified of public speaking.