Correct answer is (d) 1080
The best I can explain: 135 can be written as 3 × 3 × 3 × 5 × 1 and 24 can be written as 2 × 2 × 2 × 3 × 1.
LCM is the product of greatest power of each prime factor involved in the numbers.
Therefore, LCM = 2 × 2 × 2 × 3 × 3 × 3 × 5 = 1080