If f(x)=1/x and x is a natural number, what CANNOT be the answer for f(f(x))?
Select the correct option.
A) 1 / 7 B) 3 C) 12 / 3 D) 6 / 6 E) 1

Rationale: answer a is impossible because the invers of 1 / x is x , and the only way to have something other than a natural number is to input something other than a natural number . with the specification that only natural numbers may be used 1 / 7 is not a possibility for f ( f ( x ) )
Answer: A