Answer:
D.) An acid and a base
Step-by-step explanation:
One part of an acid is H+ and the other part is a negatively charged ion. One part of a base is -OH and the other part is a positively charged ion. When an acid and base react, the H+ and -OH combine to form water and the ions combine to form a salt.
The others are incorrect because they do not guarantee that water (H2O) and a salt are products.