It began 3.5 billion years ago
The correct option is IT CAN FORM FOUR COVALENT BONDS.
Carbon is capable of forming four covalent bond in order to attain the octet form, this gives it the ability to combine with different elements in different ways. The ability to combine with different elements makes carbon to be abundant on the earth, because it is found in variety of different substances.
The answer is amyloid beta. They clump together and form plaques. The formed plaque can block signals transmitted from one cell to another cell. In addition, the plaque can cause swelling, especially in the area where it is formed. It can also digest the disabled cells. This type of plaque is very common among patients with Alzheimer's Disease.
Ok I think its small polar molecules but I could be wrong.