Answer:
a. acid is always added to the base.
Step-by-step explanation:
An acid-base titration is a laboratory experiment carried out to determine the unknown concentration of a base or acid by method of neutralization. Neutralization is the reaction between an acid and a base.
In the experiment set-up, the known concentration of acid is placed in the BURETTE while the base is pipetted into a conical flask. The acid is gradually added to the base, which contains an indicator, until a color change is observed. Hence, acid is always added to the base in an acid-base titration.