Answer:
the first graph on the left
Explanation:
Substitute the x- coordinate of the point indicated on the graph into the equation and check that this gives the value of the y- coordinate
(1, 6) ⇒ f(1) = 2
= 2 × 3 = 6 ← correct
(1, 9) gives y = 6 ≠ 9 ← not valid
(2, 8) ⇒ f(2) = 2
= 2 × 9 = 18 ≠ 8 ← not valid
(2, 12) gives y = 18 ≠ 12 ← not valid