When the applied force on the body is constant, it will move as follows:

Newton first  law states that unless compelled by an external force, a body will remain at rest or in uniform motion in a straight line. If and only if the resultant force on the body is zero, it remains unaccelerated.

Newton's first law of motion states that when a force is applied to a body, its velocity changes, causing the momentum to change as well because momentum is proportional to velocity.

When a force is applied in the direction of motion, the speed of the body increases, and vice versa, so the speed may vary when the force is applied to the body.

If the applied force is constant, the body will move at the same rate. As a result, option 3 is correct.