A wheel of radius $R$ rotates with constant angular acceleration $$ about an axis passing through its center. What is the ratio $\frac{a_1}{a_2}$ of the tangential accelerations $a_1$ of a point a distance $\frac{R}{2}$ from the center, and $a_2$ of a point at distance $R?$

A$)4$

B$)2$

C$)1$

D$)0\mathrm{.}5$

E$)0\mathrm{.}25$