Answer:
C. 75
Step-by-step explanation:
First, list the multiples of each numbers and stop when you reach the least common multiple (the smallest number the numbers can multiply up to):
5: 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75 . . .
25: 25, 50, 75 . . .
15: 15, 30, 45, 60, 75 . . .
5 times 15 is 75, 25 times 3 is 75, and 15 times 5 is 75. Their LCM is 75.