which statement about linear functions are true

Question

A)linear functions grow by equal factors over equal intervals
B)linear functions grow by equal differences over equal intervals
C)linear functions grow by equal differences over unequal intervals
D)linear functions grow by unequal factors over equal intervals

I think the answer was A, is this correct? If not can you help explain this.
Thanks for your help.

Answer 1

Better check B.

It's the differences that are constant, not the ratios. A gives an exponential function.

Consider y = 2^x

when x grows by 1, y doubles.

But, if y = mx+b (a linear function)

when x grows by 1, y grows by m, and the difference is constant over equal intervals.