$(2$ points$)$ If a planet had twice the Earth's mass and twice its radius, the acceleration due to gravity at its surface would be

a$.,2\mathrm{.}45\frac{m}{s^2}$

b$.4\mathrm{.}90\frac{m}{s^2}$

c$.9\mathrm{.}80\frac{m}{s^2}$

d$.19\mathrm{.}6\frac{m}{s^2}$

e$.39\mathrm{.}2\frac{m}{s^2}$