The correct option is D 60
To find the smallest number of chairs that can be arranged in either 12 or 15 rows, we find the LCM of 12 and 15.
212,153 6,152 2, 55 1, 5 1, 1
LCM = 2 × 3 × 2 × 5
= 60
60 chairs is the minimum number of chairs that can be arranged in either 12 rows or 15 rows completely.