If frost has formed and clouds arrive what may happen to further temperature fall?

Correct answer: Clouds can reduce further radiational heat loss

Direct answer: B is correct. On a clear night, the ground can lose energy by emitting infrared radiation to the colder sky, so its temperature may continue to fall and frost can form. When clouds arrive, they absorb and re-emit much of the outgoing long-wave radiation back toward the surface. This reduces the net radiational cooling of the ground and can slow or limit any further temperature decline. The clouds do not necessarily warm the surface immediately, and the exact result depends on cloud thickness, moisture, wind, and other conditions; the safe conclusion is that they can reduce further heat loss. A is wrong because temperature cannot fall infinitely. C is wrong because clouds do not always remove all water vapour. D is wrong because frost remains ice, not rock. Memory cue: clear skies favour rapid night cooling; cloud cover acts like a blanket.