Which describes the greenhouse effect?

I don't understand your question but here's an answer

Explanation:

The greenhouse effect is a process that occurs when gases in Earth's atmosphere trap the Sun's heat. This process makes Earth much warmer than it would be without an atmosphere. The greenhouse effect is one of the things that makes Earth a comfortable place to live.

Natural process.

Explanation:

Greenhouse effect is a natural process that arms up earth’s atmosphere. Sun radiations when hit the ground are absorbed and some reflected back to the atmosphere and absorb by the greenhouse gases. These rays maintain the temperature of earth’s surface and keep it warm.

But due to excessive human activities, greenhouse effect is high and making the earth hotter.  

your answer is "the 1950's"

i thinking chemical change