Differentiate between kidneys and lungs​

Kidneys are used to excrete urine and toxic wastes. They are very essential for keeping the body clean. Usually it excretes urea, sodium and some salts which are considered as waste in the body.

Lungs are used to breathe in and out air. It helps us to stay alive. We breathe in oxygen rich air and breathe out foul carbon dioxide air.

if your own plato the answer is b. the fern transitioned from sporophyte generation to gametophyte generation.