Question

waves move fastest in
low - temperature gases.
low - temperature solids.
high - temperature gases.
high - temperature solids.

Explanation:

The speed of waves depends on the medium. Solids have particles closely - packed compared to gases, allowing waves to travel faster in solids. Also, higher temperature generally increases the kinetic energy of particles in a medium, which can increase wave speed. So waves move fastest in high - temperature solids.

Answer:

high - temperature solids.