Function of excretory systems including skin and lungs

Oh god, you do realize how big that question is right? There are many functions but to name a few, the lung help removes carbon dioxide within our body as a product from the mitochondria in our cells. our skin excretes sweat which in turns evaporates, allowing our body to cool down. Our skin also excretes a slightly acidic chemicals onto our skin to kill bacteria. Of course, not to forget; our excretory system removes waste and helps nutrition absorption in our food with a little help from some microorganisms.    

Nimbostratus is the correct answer.
explanation: nimbostratus clouds are the type of clouds that are mostly likely present on gray, rainy day. these clouds produce continuous rain, snow and there is no thundering or lightening either.

They both have rock surfaces