Answer:
D)phenolphthalein
Explanation:
Phenolphthalein is an acid base indicator. It is used in acid base titrations. It is colorless in acidic solution and turns pink in basic solutions. Between 8-10 pH range phenolphthalein is pink and at pH below 8 it is colorless.
Hydrochloric acid is an acid, sodium hydroxide is a base and water is neutral.
