Answer:
Book lungs
Explanation:
The horse shoe crab has a hard outer surface carapace which has the shape of a horse shoe.
It has book lungs which come in 5 sets. The lungs are usually found on the ventral side of the crab.
The book lungs acts as gills which is used in breathing when the horseshoe crab is in water . The book lungs also helps the crab to breathe on land for a certain period of time provided the lungs are moist.
D, because skin tans to help us stand being in the sun without getting burned.
An example of physiological adaption is being able to digest milk. Before, humans were not able to digest milk before we developed enzymes that now make us have the ability to do so, thus allowing us another food source.
We should stop polluting the rivers and throwing trash all over the place, and cut down less trees, since we are harming the environment for the animals and plants.