It will be when you delete "upon it" and change the comma to a semicolon.
Student or Learner
It's your prerogative, you decide upon it.
Is the above sentence correct?
Why "upon" is not correct?
'Decide upon' means 'choose', which might not fit the OP's sentence.
I am not a teacher.
I agree with Mike. It's completely wrong.
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.