What are the macro-scale appearances and molecular-scale behaviors of a gas, liquid, and solid?
a) Gas fills container with no visible shape; liquid flows and takes shape of container; solid is rigid and keeps its shape.
b) Gas has no defined volume; liquid takes shape of container; solid flows easily.
c) Gas is rigid and keeps its shape; liquid fills container with no defined volume; solid has no visible shape.
d) Gas flows and takes shape of container; liquid is rigid and keeps its shape; solid fills container with no defined volume.