Step 1: Understanding the Concept
The question asks for the number of neutral colours. Neutral colours are colours that are not found on the traditional colour wheel and lack strong chromatic content.
Step 2: Detailed Explanation
The primary neutral colours are:
1. Black
2. White
3. Gray (which is a mixture of black and white)
Sometimes, browns and beiges are also considered neutrals, but the core group consists of these three. Given the options, "three" is the most standard and widely accepted answer.
Step 3: Final Answer
There are three main neutral colours: Black, White, and Gray.