HELP MEEE PLZZ I DON'T KNOW WHAT TO PUT BTW THIS IS BIBLE! Why did John Mark leave the group?

I just did research and this is what I found

Explanation:

Some men a whole lot smarter than me have speculated about the possibility that Mark left them and returned to Jerusalem to alarm the church, reporting that Paul received Gentiles apart from going through the synagogue. It is definitely of worth to note that the conversion of Sergius Paulus came right before Mark’s decision to leave. If Mark did in fact alarm the church, it may have stirred up the controversy we find later in Acts 15.1.

I'm not religious, so I don't know much about the bible, but this is what I found in my research, so I hope it's correct.

it would be a. that is the only one i could think of