The answer is D to this question
<h2>Answer </h2>
Option A - Stratified sampling
<u>Explanation</u>
The student used Stratified sampling as in the following process the student divided the students of the high school into equal subgroups before sampling. Then a random sample is drawn from each group. Members in Sophomore, Junior, and Senior classes may not be fixed as they are picked on random bases. However, the objective is to improve the accuracy of the sample when the population size is too large.
Answer:
The amount of carbonate, a main building block in sea water, is reduced by ocean acidification. This makes it harder for marine organisms to shape their shells and skeletons, such as coral and some plankton, and existing shells will begin to dissolve.
