In which example has the value of a primary colour changed while its basic hue family remains?

Correct answer: Adding white to red to make pink

The governing concept is the difference between hue and value. Adding white to red makes a lighter red, commonly called pink or a red tint; the value changes while the red hue family remains. Therefore option A is correct. Mixing two primaries to make orange, green or violet changes the resulting hue family itself, so options B, C and D do not meet the condition.