Sabrina is using an online calculator to calculate the outputs f(n) for different inputs n. the ordered pairs below show sabrina's inputs and the corresponding outputs displayed by the calculator:
(1, 6), (2, 11), (3, 16), (4, 21)
which of the following functions best represents the rule that the calculator uses to display the outputs?
f(n) = 5n − 1
f(n) = 5n + 1
f(n) = 4n + 3
f(n) = 4n − 3