Ans. Option (C).
Non-specific immune responses include immune responses, which are same for all pathogens. Immune cells or components that elicit non-specific immune responses may internal (such as neutrophils and macrophages) and external (such as tears, saliva, and sweat).
Sweat glands secrete sweat that provides an acidic environment onto the skin that slows down the growth of pathogens and shows an non-specific external response.
Thus, the correct answer is option (C).