The function f has the property that for each real number x in its domain, 1 / x is also in its domain and

f(x)+f\left(\dfrac{1}{x}\right)=x

What is the largest set of real numbers that can be in the domain of f ?

**Answer Choices**

A. \{x \mid x \neq 0\}

B. \{x \mid x<0\}

C. \{x \mid x>0\}

D. \{x \mid x \neq-1 and x \neq 0 and x \neq 1\}

E. \{-1,1\}