Final answer:
The least common multiple of 31, 18, and 20 is 180. Hence the correct answer is option A
Step-by-step explanation:
To find the least common multiple (LCM) of 31, 18, and 20, we need to determine the smallest number that is divisible by all three numbers.
We can list the multiples of each number and find the smallest number that appears in all three lists.
The multiples of 31 are: 31, 62, 93, 124, 155, 186, 217, 248, 279, 310...
The multiples of 18 are: 18, 36, 54, 72, 90, 108, 126, 144, 162, 180...
The multiples of 20 are: 20, 40, 60, 80, 100, 120, 140, 160, 180, 200...
The smallest number that appears in all three lists is 180. Therefore, the least common multiple of 31, 18, and 20 is 180.
Hence the correct answer is option A