Hint:To answer this question, we first need to understand what is inertia. Inertia is a property of a body that resists any force that tries to move it or change the magnitude or direction of its motion if it is already moving. Inertia is a passive property that prevents a body from doing something other than resisting active agents including forces and torques.
Complete answer: Inertia of direction: A body moving in one direction cannot change its direction without the application of force. It's the property that allows a body to keep its sense of direction.As explained in the above also about the inertia of direction so the tendency of inertia of motion tries to keep it in the same direction.
Therefore, when a bus makes a sharp turn due to inertia of motion the passengers tend to move in the straight direction in which they were moving previously. So that’s why the passengers tend to fall sideways as they try to be in the straight-line motion.
So, the correct answer is option C.
Note:Any force invoked by an observer to preserve the truth of Isaac Newton's second law of motion in a reference frame that is spinning or otherwise accelerating at a constant rate is known as inertial force. See centrifugal force, Coriolis force, and d'Alembert's theory for more information on basic inertial forces.