Your answer is the last option, 7 or 12.
We can write this question as an equation, if we call the number ‘x’:
(x - 9)² = x - 3
Then we can expand the bracket and solve for x:
x² - 18x + 81 = x - 3
x² - 19x + 84 = 0
(x - 7)(x - 12) = 0
x = 7 or x = 12
The factorisation is a bit difficult so you could also use the quadratic formula to get to the same answer.
I hope this helps! Let me know if you have any questions :)
