Why is it often colder on cloudy summer days?

A. More sunlight is reflected than transmitted by the dark lower layers of clouds.

B. More sunlight is reflected than transmitted by the dark lower layers of clouds.

C. More sunlight is reflected then transmitted by the white upper surface of clouds.

D. More sunlight is transmitted than reflected by the white upper surface of clouds.

I was thinking A is that correct?

Yes, A is correct.