WILL MARK BEST AND FIRST CORRECT ANSWER THE BRAINLIEST
Kathryn babysits for extra money. She uses the function f(x) = 10x + 18 to calculate her earnings each day, where x represents the number of children she babysits. What is the domain of the function?

A.
{28, 38, 48, . . .}

B.
all positive integers

C.
{18, 28, 38, . . .}

D.
all integers