If air speed is greater along the top surface of a bird's wings, pressure of the moving air there is

unaffected

reduced

increased

turbulent

By Bernuolli's equation we know that

now since we know that height is almost same for two sides of wing

now we will have

now pressure on lower side of wing must be more than the pressure on the upper side

so speed on the top is more than the speed at the bottom

so correct answer will be

If air speed is greater along the top surface of a bird's wings, pressure of the moving air there is REDUCED.