At a glance, Kendra believes that the function represented on the graph is linear.

How can Kendra determine if the function is actually linear?

She can check to see if the rate of vertical increase equals the rate of horizontal increase between each pair of points.
She can check to see if the sum of each y-value and x-value in every ordered pair is the same.
She can check to see if the quotient of each y-value and x-value in every ordered pair is the same.
She can check to see if the rate of change between the first two ordered pairs is the same as the rate of change between the first and last ordered pairs.