Which of the following statements is true?

Caves are formed through oxidation.
The movement of sediment is called weathering.
Water expands when it freezes.
Rocks usually absorb heat evenly.

Some gamma ray bursts are hypothesized to come from mergers of neutron stars or black holes. if this hypothesis is correct, what else should we in principle be able to detect from such mergers? a. gravitiational waves b. x-ray bursts c. significant disruption of gas thousands of light-years away in the surrounding galaxy d. an "afterglow" of bright visible light, lasting for weeks