A level physics

An aerospace engineer has built two differently designed wings. One wing is made from
an aluminium alloy and the other is made from a carbon fibre composite.
The engineer tests a sample of each material by applying a varying stress.
Tick two of the boxes to indicate which are properties of the material
from which the wing is made.

breaking stress
stiffness constant, k
tensile strain
tensile stress
Young modulus

The answer is breaking stress and Young modulus. Why is stiffness constant not a property? and also intuitively I know that stress and strain would change if the shape of the object changes but could someone explain why with actual physics.

Breaking stress and Young modulus are material properties, properties the material has regardless of the shape of the object.

Tensile sress depends on the shape and the load applied.
Stiffness constant depends on the material and the shape/size of the object e.g you can make springs of different stiffness out of the same material by making the coils out of thicker wire.

Thank you so much for explaining it’s helped a lot! But quick question wouldn’t the breaking stress change depending on the shape too for example if 2 wire were made of the same material but one is a lot thicker the thicker one would have a higher breaking stress stress no?