Answer the following question: Fact 1: Agreenhouse is used to protect plants by keeping them warm. Fact 2: Energy from the sun keeps the earth warm, enables plants to grow. Given the two facts above, greenhouses are used to what, using the energy from the sun?

Available choices:
[a]. heat skin.
[b]. evaporation.
[c]. protect plants.
[d]. cool air.
[e]. spread flower seeds.
[f]. important habitats.
[g]. food and shelter.
[h]. reserve water.
Answer:
[c].