D would be the correct answer
Answer:
takes in carbon dioxide, puts out oxygen
Explanation:
Answer:
The three layers of smooth muscle consist of the outer longitudinal, the middle circular, and the inner oblique muscles. Construction of these muscles helps mix and break the contents into a suspension of nutrients called chyme and propels it into the duodenum.
The electrons in the outermost shell of the covalent compounds are shared by nearby atoms. As there are no free electrons for conducting electricity, the covalent compounds are perfect insulators at absolute zero. As the temperature increases, some electrons move from valence band to conduction band. This gives rise to conductivity. But as the numbers of charge carriers are very low, covalent compounds are poor conductors. On the other hand metals are good conductors cause of their bonding. Metallic bonding consists of a sea of electrons rather than discreet bonds. The free electrons are able to move freely. Since electricity and heat need electrons to move, the bonding promotes conductivity.
Well theory isnt proven. It means you have a strong idea about the subject your talking about. So if a scientist finds evidence that suggests something against the theory then it can be changed.
