Which feature distinguishes vegan shampoos from regular shampoos?

Vegan shampoos are distinguished by their formulation, which specifically excludes any ingredients derived from animals. This means they do not contain substances such as keratin, honey, beeswax, or any other components that come from animals. The focus of vegan products is not only on avoiding animal-derived ingredients but also on promoting ethical consumption, which resonates with consumers who are concerned about animal welfare.

In contrast, the other options touch on aspects of shampoo formulation or marketing that do not specifically pertain to vegan standards. For instance, stating that it contains only synthetic ingredients does not inherently imply it is vegan, as synthetic ingredients can also be created in a way that may not align with vegan principles. The claim of having a higher concentration of active ingredients doesn't define vegan products, as both vegan and non-vegan shampoos can vary in formulation strength. Lastly, vegan shampoos can be found in various retail settings, not exclusively in salons, further differentiating their availability beyond just salon offerings. Thus, option B accurately captures the essence of what makes a shampoo vegan.