What is the main difference between adding white and adding black to green?

Correct answer: White creates a tint and black creates a shade

The governing concept is the difference between a tint and a shade. White increases the lightness, or value, of green and produces a lighter green tint. Black decreases the value and produces a darker green shade. Therefore B is correct. The terms are not interchangeable, and neither white nor black changes green into a primary colour; they only modify its lightness and darkness.