The correct answer is 'increase the mass of the egg.'
The force experienced by the egg is called the gravitational force.
The egg applies a force equal to the gravitational force on the floor upon collision. And according to Newton's third law, the force, in turn, exerts a force on the egg. This is called the normal force.
Thus, according to newton's second law, the force experienced by the egg upon landing is given by,
Where m is the mass of the egg and g is the acceleration due to gravity.
From the above equation, we can see that the force is directly proportional to the mass of the egg. Thus increasing the mass of the egg increases the force experienced by the egg.
From the above equation, we can see that the drop height does not affect the force experienced by the egg.
The changing in the time of collision changes the impulse experienced by the egg and does not affect the force experienced by the egg. And changing the surface will change the duration of the collision and hence changes the impulse experienced by the egg. But it will not affect the force experienced by it.
Thus the correct answer is "increase the mass of the egg."