About 2 mL of acetic acid was taken in each of the three test tubes P, Q and R and 5 mL, 10 mL and 15 mL of distilled water were added to them, respectively. Instantaneously, a clear solution is observed in the test tubes _______.
(A) P and Q only (B) Q and R only
(C) R and P only (D) P, Q and R
