The difference between linear and exponential functions is that,
Linear functions change at constant rate per unit interval
Exponential function changes by a common ratio over equal intervals
The given expression is (5x)^3
The table would be
x y
0 (5 * 0)^3 = 1
1 (5 * 1)^3 = 125
2 (5 * 2)^3 = 1000
3 (5 * 3)^3 = 3375
4 (5 * 4)^3 = 8000
The values of y is not increasing by a common ratio. Thus, it is not exponential
It is not linear because the rate of change is not constant rate per unit interval
Thus, the correct option is D