PLEASE HELP! I NEED THE ANSWER NOW!! please 15 points
Which of the following describes a linear function?
A: It is V-shaped and passes through the origin.
B: It is a straight line in one portion and a curve in another portion.
C: Its y-values decrease at a constant rate as its x-value increases.
D: Its y-values increase at a nonconstant rate as its x-value increases.