(the Domain of the function is clearly all Real numbers - {0})
The Range is the set of all values that the function can take.
let c be any value in the range. So c=1/x for some x in the domain,
and so x=1/c.
For example, is c=10 in the range of the function?
yes, for x=1/10, f(1/10)=1/(1/10)=10.
Consider again x=1/c, the only value of c that cannot be in the Range is c=0, because to produce 0 in the range, x would need to be 1/0, which is undefined.
Answer:
B.
all real numbers except 0
