Answer:
7 m/s (agrees with answer a in your list)
Explanation:
Recall that the centripetal acceleration is defined by the square of the tangential velocity divided by the radius of the rotational motion:
[tex]a_c=\frac{v_t^2}{R}[/tex]
then the tangential velocity is extracted from here as:
[tex]a_c=\frac{v_t^2}{R} \\v_t^2=a_c * R\\v_t=\sqrt{a_c * R}[/tex]
in our case, this becomes:
[tex]v_t=\sqrt{7*7} = 7 \,\,m/s[/tex]