Question

If Earth were to experience a runaway greenhouse effect, its atmospheric conditions would resemble those of which planet?

Answer 1

Venus, with its heavy carbon dioxide-rich atmosphere.

Explanation:

Dcientists study the Venusian armosphere as a model of the runaway greenhouse effect, and to better understand the effects of pollutants in our own atmosphere.

See https://en.wikipedia.org/wiki/Runaway_greenhouse_effect.