Question

rewatch
question 3
3/5
how does a physical greenhouse keep plants warm?
it is built underground to insulate from cold.
it has glass walls and a roof that trap the suns heat inside.
it generates its own light.
it uses an internal heating system.

Explanation:

Greenhouses rely on the greenhouse effect: glass (or transparent plastic) allows sunlight (shortwave radiation) to enter and warm the interior surfaces. These surfaces then emit longwave infrared radiation, which cannot pass back through the glass, trapping heat inside to keep plants warm. The other options are incorrect: most greenhouses are above-ground, they do not generate their own light, and basic physical greenhouses do not require an internal heating system to retain warmth from the sun.

Answer:

It has glass walls and a roof that trap the sun's heat inside.