Answer:
D. 5
Explanation:
You want the constant of proportionality in the relation shown by the graph.
Constant of proportionality
A proportional relation has the equation ...
y = kx . . . . . . . . where k is the constant of proportionality
When x=1, this becomes ...
y = k
The value of y when x=1 is marked on the graph: y = 5 at that point, so ...
k = 5
The value of the constant of proportionality is 5.