how is it possible??

I think this question is missing a condition that n must be an integer. and statment 1 should read tenths digit?

if the tenths digit of 1/n = 0 then and n is a single digit integer then n must = 1. To test this you can try a few numbers

1/1 = 1.0, 1/2 = .5, 1/3 = .333 (at some point you can either try all numbers or realize that with a numerator of 1 and a denominator between 2 and 9 you will always get a value > 0 for the tenths digit)

therefore 1 is Sufficient.

the units digit of 1/n>=n then you also know that n must = 1

1/1 = 1 but 1/2= 0.5 - any other fraction that fits the pattern will have a units digit of zero. Thus D is the answer

However, without the condition that n is an integer, it does not work.

Statement 1 would then mean that n could equal 1, 1/2 or any fraction between 1 and zero
because 1/(1/2) = 2.0

Statement 2 would similarly not work because 1/n>=n will result in a similar option of 1 (as shown above) or 1/2 because 1/(1/2) = 2 which is greater than 1/2.