15/22 is the only proper fraction because its numerator (the top number) is less than the denominator (the bottom number).
Why the other answers aren’t proper:
8/8 may look like a proper fraction, but it isn’t. Proper fractions are also supposed to be less than 1, but this fraction is equivalent to 1. Also 12/9 and 3/2 are both improper fractions because their numerators are bigger than their denominators.
