Which of the following is a sign of acute inflammation?

• A. Swelling
• B. Improved function
• C. Decreased redness
• D. Reduced temperature

Answer: (A)

Swelling is a hallmark feature of acute inflammation because chemical mediators increase the permeability of nearby capillaries, causing fluid and proteins to leak into the surrounding tissue. That fluid accumulation, or edema, makes the area visibly swollen and felt as puffiness or tautness. The process starts with vasodilation and increased blood flow, which also leads to redness and warmth, but the edema itself is the direct sign of fluid leaving the vessels and collecting in the tissue.

Other possibilities don’t fit as well: improving function isn’t typical—acute inflammation often reduces function due to swelling and discomfort; redness is usually present and increased, not decreased; and the local temperature tends to rise rather than fall. So swelling best represents the acute inflammatory response in this context.