Observe the data table carefully.
The values of 'x' are in increments of 1.
And it is observed that the function values H(x) are in increments of 6. Since the increments in the function is constant, it can be claimed that the given function is linear.
Moreover, the function would have been exponential if the ratio of a function value to its preceding value was constant. But this is not true in this case. So the given function is not an exponential function.
Therefore, the 3rd option is the correct choice.