Atravel agency made the table below to represent the profits it make on a certain vacation package.

number of people vs. profit
number of people who buy the package, x
profit per person (in dollars), f(x)
10 500
20 800
30 900
40 800
50 500

which of the following explains the best model for the data in the table?

a)an absolute value function since the values increase and then decrease
b)an exponential function since the ratio of the y-values are about the same.
c)a linear function since the function changes at a rate of 30 dollars per person
d)a quadratic function since the points are symmetric about the line x = 30