Edwin Hubble found out that what appeared to be large clouds in space were not gas, but _

A: galaxies
B: the Oort cloud
C: comets
D: large stars

The body is protected against harmful flu viruses by

Which best explains how a heat pump can heat a room? cold air from the house is moved through pipes, where it absorbs thermal energy. warm air from outside is pushed into the house to replace the cold air. combustion warms the air when chemical energy is transferred to thermal energy. fuel is used to move a piston, which pushes warm air into the house.

Explain the significance of the increased cell specialization of the volvocine line