Consider a solution which is 0.15 M in HF and 0.10 M in KF. Which response contains all the true statements, and no others?

I. If NaOH is added, potassium ion reacts with hydroxide ion.

II. If a small amount of NaOH is added, the pH increases very slightly.

III. If HNO3 is added, hydrogen ion reacts with fluoride ion.

IV. If more KF is added, the pH decreases.

A. I, III, and IV

B. II and III

C. II and IV

D. III

E. another combination.