in general there are rhree states of matter
1. Solid
2. liquid
3.Gas
Solids are characterized by a fixed shape and volume. They do not change their shape and volume with container as the particles in them are closely packed and have strong intermolecular forces of attraction.
In case of liquids they have definite volume however they do acquire the shape of container. the molecules less closely placed than solid as they have weaker intermolecular forces of attraction as compared to solids.
Gas has neither definite shape not definite volume.
They have weakest force of attractions
hence answer is
State A: changes shape and volume, muat be a gas
State B: changes shape but not volume , must be a liquid
State A: oxygen gas
State B: juice