thermometers ... (a, b,c,d,or e)?

thermometers ...

a. rely on materials that expand when heated and contract when cooled.

b. like an old mercury thermometer rely on the collisions between molecules in the object whose temperature is to be measure with the molecules in the thermometer itself

c. like Galileo's relied on the change in density of a fluid with temperature, in combination with the buoyancy of objects that float in the liquid.

d. all above

e. a and c only