Option B
2000=2^4*5^3
No of divisor =(4+1)*(3+1)=5*4=20
For any number n total no of divisor is given by
n=p1^a1*p2^a2...
Where p1,p2 are prime numbers
Then no of divisor =(a1+1)*(a2+1)...
This can be explained using counting...We take prime so it cannot be further factorised so take this que as example
2000=2^4*5^3
In this lets take 5^3
We can take 3 5 or 2 5 or 1 5 or 0 5 so 4 ways similarly for 2^4 5 ways
Therefore total ways=5*4=20