Select the correct answer. Why is carbon considered tetravalent?

A. Since it has four electrons in its outermost orbital, it needs four more electrons to complete its octet.

B. Since it has two electrons in its outermost orbital, it needs four more electrons to complete its octet.

C. Since it has four electrons its outermost orbital, it can donate four electrons to complete its octet.

Dna is colied into chromosomes in a cell

The sketch shows a rynchosaur, an extinct animal that is known only from fossils. there has been much debate about the classification of these creatures. some scientists suggest that they belong with primitive amphibians, and some think they are related to snakes and lizards.the data equally support both cases. which statement best explains how to draw a cladogram that includes the rynchosaur? draw the cladogram for amphibians. draw the cladogram for reptiles. draw two cladograms, both showing the traits, and leave it as a hypothesis. draw two cladograms, both showing the traits, and have scientists vote

The nervous system interacts with the endocrine system by a. using hormones as connections b. sending nerve impulses directly to glands c. using neuroendocrine cells as connections d. sending neurotransmitters directly to neurons