Classify the Function as a Polynomial Function, Rational Function, or Root

Multiple Choice

Classify the function as a polynomial function, rational function, or root function, and then find the domain. Write the domain in interval notation.
-f(x) = 5x - 1

A) polynomial function; $( - \infty , 0 ) \cup ( 0 , \infty )$
B) polynomial function; $( \infty , \infty )$
C) polynomial function; $( 0 , \infty )$
D) polynomial function; $[ 1 , \infty )$