1. The process by which organisms best suited to the environment survive is called
A natural selection
B equilibrium
c frequency
D coordinated stasis

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.

Try and make the question more clear : )

Air enters through the nose (and sometimes the mouth), moves through the nasal cavity, the  pharynx, the  larynx, enters the  trachea, moves through the  bronchi  andbronchioles  till the alveoli.