What is the purpose of culture media such as MacConkey agar and blood agar?

• A. MacConkey is selective/differential for Gram-negative enterics and lactose fermentation; blood agar is nonselective and shows hemolysis patterns.
• B. MacConkey agar grows only Gram-positive bacteria; blood agar is selective for anaerobes.
• C. MacConkey agar is used to culture fungi; blood agar differentiates by colony size.
• D. MacConkey agar grows only viruses; blood agar grows only Gram-positive cocci.

Answer: (A)