Healthy skin contains colonies of:

• A. Infection
• B. Bacteria
• C. Grease
• D. Water

Answer: (B)

Healthy skin hosts a resident population of bacteria—the normal skin microbiome. These bacteria live on the surface and in hair follicles and sweat glands, and they’re usually harmless and even beneficial. They help protect the skin by occupying space and resources, making it harder for pathogens to take hold, and by producing substances that inhibit harmful microbes. Because of this, healthy skin isn’t sterile; it naturally carries a stable community of bacteria. Grease refers to sebum, a lipid secreted by glands, not a bacterial colony. Water isn’t a living colony. The key idea is that a normal, commensal bacterial population is part of healthy skin rather than infection or any non-biological substance.