function main mneu wont run [on hold]

I have practised some code and put it all together but I'm not sure why it wont run, I'm not great at python and the mistakes are probably obvious but I don't know what's wrong with it, please help! I haven't quite finished and when I run it no errors or code appears.

def mainMenu():
    print("Welcome to my quiz!")
    print("1, Are you a student?")
    print("2. Are you a teacher?")
    print("3. quit")
    selection=int(input("Enter choice: "))
    if selection == "1":
        student()
    elif selection == "2":
        teacher()
    elif selection == "3":
        exit
    else:
        print("Invalid choice, please choose an option")
        mainMenu()