You can turn them all into decimals:
2/7 = 7/10 becomes 0.285 = 0.7 which is not true.
3/5 = 9/15 which becomes = 0.6 = 0.6 which is true.
1/2 = 2/3 becomes 0.5 = 0.666 which is not true.
1/4 = 3/8 becomes 0.25 = 0.375 which is not true.
So the correct answer is 3/5 = 9/15