An unbanked curve has a radius of 60 m. The maximum speed at which a car can make a tum, if
the coefficient of static friction is 0.75, is 

• A

  2.1 $m{s}^{-1}$

• B

  14 $m{s}^{-1}$

• C

  21 $m{s}^{-1}$

• D

   7 $m{s}^{-1}$