Which of the following is a common source of biotin?

Biotin, also known as vitamin B7, is a water-soluble vitamin that plays a crucial role in carbohydrate, fat, and protein metabolism. It is commonly found in a wide range of foods, making it readily available in various diets. Sources of biotin include eggs, nuts, seeds, fish, meat, dairy products, whole grains, and certain vegetables like cauliflower and spinach. This broad distribution across many food categories explains why it is classified as being "widely found in foods." Therefore, this choice accurately reflects the diverse sources from which individuals can obtain biotin.

Other options limit the sources of biotin to specific food groups, which does not accurately represent the abundance of biotin in a balanced diet. By highlighting the wide availability of biotin across different food categories, the correct answer underscores the importance of a varied diet in meeting nutrient needs.