Answer: (2) Ink filler
Bernoulli’s principle states that the total mechanical energy of the moving fluid comprising the gravitational potential energy of elevation, the energy associated with the fluid pressure and the kinetic energy of the fluid motion, remains constant.
With the aid of lift on its wings, an aircraft wing changes its vertical position. The area below the wing is at high pressure and at lower area is at low pressure. This pressure difference causes the uplift.