In an experiment, acid was added to two solutions:

Solution 1: distilled water only

Solution 2: distilled water containing sodium bicarbonate

Then, the pH of each solution was taken.

Solution 1 had a final pH of 4.5, while Solution 2 had a final pH of 6.8.

Which of the following statements explains the difference between the two solutions?

Choose 1

(Choice A)

Sodium bicarbonate increases the temperature of a solution, which helped raise the pH of Solution 2.

(Choice B)

Hormones released in Solution 2 allowed it to maintain a higher pH.

(Choice C)

The water in Solution 1 had a lower starting pH than the water in Solution 2.

(Choice D)

Sodium bicarbonate acted as a pH buffer in Solution 2.