Which characteristic differentiates exotoxins from endotoxins?

• A. Exotoxins are heat-stable, while endotoxins are heat-labile
• B. Exotoxins are secreted by living bacteria, while endotoxins are released upon bacterial death
• C. Exotoxins are lipopolysaccharides, while endotoxins are proteins
• D. Exotoxins are only produced by Gram-positive bacteria

Answer: (B)