Common reasons for colour change include?

The option "All of the above" is correct because it encompasses a variety of factors that can lead to changes in hair color. Each of the individual options contributes to the overall understanding of why color changes may occur.

Time of year influences hair color due to environmental factors like sunlight exposure and humidity. For example, in the summer, UV rays can lighten hair, while the winter months might affect hair health due to dryness.

A client's health can also play a significant role in how hair color appears. Changes in diet, hormonal balances, and medications can all impact the hair's structure and color. Conditions like stress or health issues can lead to changes in pigmentation or even hair loss, which can further affect how color is perceived.

The brand of products used can influence hair color as different brands have varying formulations that affect the hair’s integrity and the longevity of color treatments. Certain products can enhance or dull the vibrancy of hair color, impacting how it looks over time.

By considering all these factors together, it becomes clear that various elements contribute to color change, making "All of the above" the comprehensive and correct choice.