Answer the following question: Fact 1: Agreenhouse is used to protect plants by keeping them warm. Fact 2: Retains heat in cold weather, reflects exterior heat in warm weather. Given the two facts above, a greenhouse is used to protect plants by doing what?

Pick from: A). reduced heat; B). colder and wetter; C). storing lawnmowers; D). holding plant pots; E). retaining heat; F). In the winter; G). food and shelter; H). starting fires;
Answer:
E).