Answer:
c. 0.816
Explanation:
Let the mass of car be 'm' and coefficient of static friction be 'μ'.
Given:
Speed of the car (v) = 40.0 m/s
Radius of the curve (R) = 200 m
As the car is making a circular turn, the force acting on it is centripetal force which is given as:
Centripetal force is, 
The frictional force is given as:
Friction = Normal force × Coefficient of static friction

As there is no vertical motion, therefore,
. So,

Now, the centripetal force is provided by the frictional force. Therefore,
Frictional force = Centripetal force

Plug in the given values and solve for 'μ'. This gives,

Therefore, option (c) is correct.