Correct option is B
Given series: 18, 23, 32, 37, 46, ?
Find the differences between consecutive terms:
23 - 18 = 5
32 - 23 = 9
37 - 32 = 5
46 - 37 = 9
The differences alternate between 5 and 9. Following this pattern, the next difference should be 5.
So, add 5 to the last term (46):
46 + 5 = 51
Therefore, the number that replaces the question mark is: (b) 51