Grooves are designed to increase friction not reduce friction, . It is increasing friction as the grooves are made for more easier interlocking of the tyre and the ground so that the car won't slip. Grooves are irregular so the ground will interlock with the tyre.

The correct answer is option 'D': Tyres have grooves to reduce the friction.

Explanation:
Friction is a force that opposes the motion of an object when it comes in contact with another object or surface. It acts in the opposite direction to the applied force. Friction plays a significant role in our daily lives and affects various aspects of motion and movement.

Friction and its types:
There are mainly four types of friction:

1. Static friction: Static friction is the force between two objects that are not moving relative to each other. It prevents the objects from moving when a force is applied.

2. Sliding friction: Sliding friction occurs when two objects slide past each other. It opposes the relative motion of the surfaces in contact.

3. Rolling friction: Rolling friction occurs when an object rolls over a surface. It is generally less than sliding friction and helps in the smooth movement of objects like wheels.

4. Fluid friction: Fluid friction occurs when an object moves through a fluid (liquid or gas). It is also known as drag and is responsible for the resistance experienced by objects moving through air or water.

Explanation of the given options:
a) A ball moving on a horizontal surface stops due to the force of friction.
This statement is correct. When a ball is rolling on a horizontal surface, the force of rolling friction acts opposite to the direction of motion and eventually brings the ball to a stop.

b) Force of friction helps us to walk on the ground.
This statement is correct. When we walk, the force of friction between our feet and the ground provides the necessary grip and traction. Without friction, it would be extremely difficult to maintain balance and move forward.

c) Wheels are spherical in shape as rolling friction is less than sliding friction.
This statement is correct. Rolling friction is generally less than sliding friction. Spherical wheels reduce the surface area in contact with the ground, resulting in a smaller frictional force and facilitating smoother rolling motion.

d) Tyres have grooves to reduce friction.
This statement is NOT correct. Tyres have grooves to increase friction and improve traction. The grooves, also known as tread patterns, help to channel water away from the contact area between the tyre and the road, reducing the risk of hydroplaning. The grooves increase the surface area in contact with the road, thereby increasing friction and providing better grip.

In conclusion, option 'D' is the correct answer as tyres have grooves to increase friction, not reduce it.