Final answer:
The correct answer from the provided options is: 2) The object loses mechanical energy.
Step-by-step explanation:
When the force applied to an object and the displacement are in opposite directions, this means that the force is doing negative work on the object. According to the work-energy principle, work done on an object results in a change in the object's mechanical energy, which is the sum of its kinetic and potential energy. If the displacement is opposite to the force, the work done by the force will be negative, which means that mechanical energy is leaving the system, and as a consequence, the object loses mechanical energy.
The concept that when force and displacement are antiparallel (opposite directions), the mechanical energy decreases can be illustrated by gravitational potential energy converting to kinetic energy when an object is in free fall; the displacement of the object is downward while the force due to gravity (weight) is also downward, resulting in an increase in kinetic energy.
However, if you push an object upwards against gravity and it moves upwards, the force exerted by you and the displacement of the object are in the same direction, increasing its potential energy. Conversely, if gravity does work on the object and the object moves downward (displacement is down and force due to gravity is down), the object's potential energy decreases, and kinetic energy may increase if the object speeds up, maintaining overall mechanical energy conservation in the absence of dissipative forces like air resistance.