Answer
(a) Exponential function
(b) Rational function
Work Step by Step
(a) An exponential function could be chosen as the model for this data since the data approximately fits the shape of an exponential function such as $2^x$(ie. increasing).
(b) A rational function could be chosen as the model for this data since it seems to have "asymptotes" in the same way that a rational function like $\frac{1}{x}$, for example, does and thus a rational function would be an approximate fit.
