Correct option is (A) 1
Assume contrary that the HCF of two consecutive natural numbers is more than 1.
Then these two consecutive natural numbers has to be divisible by that number (HCF of both consecutive natural numbers).
Therefore, minimum difference between both consecutive natural numbers must be that number which is greater than 1. This contradicts the fact that difference between two consecutive natural numbers is 1.
Hence, our assumption was wrong.
Therefore, HCF of two natural numbers is 1.
