You have the folowing function:
f(x) = 2(3)ˣ
In order to determine which of the given graph belongs to f(x), you verufy if the given points of the graphs correspond to f(x). You proceed as follow:
For first graph:
x = 1
f(x) = 2(3)¹ = 2(3) = 6
The point is (1,6)
The previous point is the same that the graph has, hence, the first graph belongs to f(x) = 2(3)ˣ
Then, it is not necessary to check the other points becasue they are not agree with f(x)