Answer:
Pandemics occur for two reasons. The first is a change in the infectious agent and the second is in human patterns. Both involve exposing people to agents they don’t have resistance to. Diseases like SARS, avian flu, and the famous Spanish flu all involved a mutation in the virus that resulted in a new disease that no one had resistance too. Examples of the second are when new groups of humans make contact, like small pox amongst native Americans, and possibly the black death.
Explanation:
<span>no because organisms such as humans are omnivores they can eat both meat and plants and may act as 1st,2nd or 3rd level heterotroph.</span>
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.
I am sure that the answer is D
