Correct Answer:
Option B - Both cumulonimbus and nimbostratus are rain bearing clouds, when looking insight, cumulonimbus forms heap and the height may reach up to 25km something but they are highly unstable as they shed rain for few minutes to hours and dissipate after that, nimbostratus are the clouds which form thin stable layer of clouds compared to cumulonimbus clouds they shed rain for several hours.
B. Both cumulonimbus and nimbostratus are rain bearing clouds, when looking insight, cumulonimbus forms heap and the height may reach up to 25km something but they are highly unstable as they shed rain for few minutes to hours and dissipate after that, nimbostratus are the clouds which form thin stable layer of clouds compared to cumulonimbus clouds they shed rain for several hours.