Hi!
The answer is B. Linear function.
A linear function is when the change in y and x is constant. For example, let's make some x and y values.
x 1, 2, 3, 4, 5
y 2, 4, 6, 8, 10
When x increases by 1, y increases by 2. The change in x and y is constant, therefore, that is a linear function.
x 6, 9, 13, 26
y 3, 5, 10, 11
There is no pattern in those numbers, therefore this is not a linear function.
Hope this helps! :)
-Peredhel