Question

the atoms in a gas will... spread out to take up any available space. stop moving after a short amount of time. move slowly until they hit a wall, then stop. stay in one place.

Explanation:

Gases have atoms with high kinetic energy, weak intermolecular forces, so they expand to fill any container/available space. Other options are incorrect: gas atoms don't stay in place (solids do), don't stop moving after short time (kinetic theory says they move constantly), and don't stop after hitting a wall (they bounce and continue moving).

Answer:

spread out to take up any available space.