By elimination: d is wrong for sure.
c is not right as there is no gland in the esophagus or the pharynx
b is also wrong as if there is no gland, then there is no enzyme and no chemical digestion in <span>esophagus or pharynx
a is the only one left.</span>
Answer A seems like the best choice for this question. Just think about some of the synonyms for therefore—”hence,” “consequently,” and “thus.” Because the adverb therefore often plays the role of a conjunction, it's sometimes called a conjunctive adverb.
B isn’t the correct answer to this question because you use “On the other hand” to introduce two contrasting points, facts, or ways of looking at something.
C isn’t the correct answer because we are not comparing or contrasting anything in this sentence.
D isn’t the correct answer because “Especially” is used in a formal sentence example: She can't be sure she will win, especially at this early stage of the campaign.
Answer:a. humans and chimpanzees share a relatively recent common ancestor.
Explanation:
Humans and chimpanzees are not evolved from one another, but both have a common ancestors. Humans share a common ape ancestor with chimpanzees who is expected to live 6-8 million years ago. The humans and chimpanzees have been evolved differently from this ancestor.
