Answer to question four is B
Marcello Malpighi was the person who used a microscope to see blood capillaries in the tail of a fish.
He was a famous Italian scientist of the 17th century, and is known as 'the father of microscopical anatomy, histology, physiology, and embryology,' so he is definitely the correct answer. Many terms in biology are actually named after this biologist.
They work together to benefit the entire organism, so that would be B
The dark plumage help them keep warm by absorbing energy from the sun