Answer:
Bubbles are a sign that the yeast is alive, and that it is performing anaerobic respiration. You should notice that the mixtures with too little and too much sugar do not grow, bubble or foam properly. This is because the yeast needs the perfect amount in order to produce carbon dioxide.
Explanation:
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.
We need classification because it is always necessary to go through different categories based on the characteristics we have so that we are able to reach the best potential answer
