Answer:
[tex]\boxed {\tt D. \ 2 }[/tex]
Explanation:
The pH stands for potential of hydrogen. It measures how acidic or basic a solution is.
If a solution has a pH of less than 7, it is acidic.
A solution with a pH of exactly 7 is neutral.
If a solution has a pH of greater than 7 it is basic.
We are looking for the most acidic. The closer the number is to 0, the more acidic it is.
The answer choices are 7, 9, 13, and 2.
2 is the closest to 0, so D. 2 is the correct answer.
