Answer: The correct answer is "liquid".
Step-by-step explanation:
The states of the matter are: Solid, liquid and gas.
Liquid: The particles of the solid are loosely packed in comparison to gas and solid. The inter molecular force between the particles are stronger than gas. It has no definite shape but volume. It takes the shape of the container.
Gas: The particles of the solid are more loosely packed. The inter molecular force between the particles are weaker than liquid and solid. It has no definite shape.
Solid: The particles of the solid are tightly packed. The inter molecular force between the particles are stronger than liquid and gas. It has definite shape and volume.
Therefore, liquid that will change shape to fit its container but has a definite volume is in a phase of matter.