Option (iv) is correct because Newton's second law of motion states that a net force produces acceleration. The context clearly indicates that acceleration occurs in the direction of the applied force (e.g., pushing a ball makes it move in the direction of the push). Additionally, it states that 'for the same object, a larger force results in larger acceleration' and 'acceleration of an object of fixed mass increases as the net force applied on it increases', which establishes that acceleration is proportional to the force acting on the object.