The glue exerts an upward force that is equal to the downward force applied by the load. Hence the correct option is d.
In this scenario, as the load exerts a strong downward force due to gravity, the glue, given its unusual strength, counteracts this force by exerting an equal and opposite upward force. According to Newton's third law of motion, for every action, there is an equal and opposite reaction.
Therefore, the glue exerts an upward force that precisely balances the downward force applied by the load. This equilibrium of forces is crucial in preventing the heavy object from falling or accelerating downward, showcasing the adhesive strength of the glue in effectively supporting the load against gravitational forces. Hence the correct option is d.