Each stroke appears different in a long colour strip. Which measure will improve uniformity?

Correct answer: Prepare enough paint for the entire area beforehand

The governing concept is consistency of mixture across one continuous painted area. Prepare enough paint in advance and mix it thoroughly so the hue, value, and thickness remain stable from the first stroke to the last. Making a new mixture for every stroke introduces variation; changing brush sizes affects application, and adding water midway changes dilution. A small extra quantity also prevents a shortage that would force an inaccurate remake. Thus option B is correct.