Islamic apologists will argue that Christians can't prove that this was written by Mark or that he had the literacy to write. This is refuted below:-
The Evidence for Mark writing the Gospel of Mark
They also argue that the Gospel of Mark (earliest Gospel) presents a "Low Christology" with Jesus as a mere human prophet claiming "High Christology" (Jesus as God) was a later "Greco-Roman fabrication" in the Gospel of John. This argument is a historical train wreck as the evidence below shows.