Answer:
The substance is in a liquid phase.
Step-by-step explanation:
The shape of a solid doesn't rely on the container it's in (think of shoes in a shoe box, the shoes maintain their shape).
The shape of a liquid can be changed depending on its container (think of water in a bowl vs. water in a bottle). Regardless of its shape, it maintains the same volume; that is, the amount of water doesn't change.
Gases don't have shapes, so that cannot be the answer either.