Final answer:
The domain of the function f(x) = 165x is all real numbers since there are no restrictions that limit the value of x for which the function is defined.
Step-by-step explanation:
The domain of the function f(x) = 165x is the set of all real numbers the value of x can take for which the function is defined. In this case, since there are no restrictions given in the function such as denominators or square roots that might restrict the domain, x can be any real number. Therefore, the correct answer is d) All real numbers.