Answer:
Multiply the air pressure by the area of the tabletop.
Step-by-step explanation:
The relationship between pressure, force and area is given by:

where in this case, p is the air pressure, F is the force exerted and A the area of the tabletop. By re-arranging the equation, we can solve for F, the force exerted:

So, the correct answer is:
The force exerted on the tabletop can be found by multiplying the air pressure by the area of the tabletop.