C is correct.
Reasoning: If the top number (numerator) is smaller that the bottom number (denominator), it means it’s smaller than 1. If, on the other hand, the numerator is bigger than the denominator, it means it’s more than 1. If youre ever unsure, devide the numerator by the denominator. This will turn the number into a decimal, and be easier to see. 8/9 = 0.88 repeated, and 3/7 = 0.4285. Therefore 8/9 is larger than 3/7. This can also be written as 8/9 > 3/7.
Good luck!