An aerofoilQuestion 11Select one:a.Must have a cambered cross-sectionb.Must have a symmetrical cross-sectionc.Must be streamlinedd.Must have reflex camber

The question seems to be incomplete. However, I can provide information based on the options given.

a. An aerofoil does not necessarily have to have a cambered cross-section. While many aerofoils do have a cambered cross-section to generate lift, it is not a requirement. Some aerofoils are symmetrical and do not have a cambered cross-section.

b. An aerofoil does not necessarily have to have a symmetrical cross-section. While some aerofoils are symmetrical, many are not. The shape of the aerofoil depends on its intended use.

c. An aerofoil must be streamlined. This is because aerofoils are designed to minimize drag and maximize lift, which requires a streamlined shape.

d. An aerofoil does not necessarily have to have reflex camber. Reflex camber is a specific design feature used in some aerofoils, but it is not a requirement for all aerofoils.

So, the correct answer is c. An aerofoil must be streamlined.