The "trial" exam is wrong.
For this sort of exam question, the expected answer is:
The upper surface of the wing generates around 2/3rds of the total lift
Usually put that way, rather than "the lower surface of the wing produces about 1/3rd of the lift", since the idea is that in a stall the wing does not lose all its lift-generating ability.
You can always tell the smart student, they read this and ask: but what if the aircraft is flying inverted!