Final answer:
Pus formation is not one of the cardinal signs of inflammation; the four primary signs are redness, swelling, pain, and local heat.
Step-by-step explanation:
The four cardinal signs of inflammation, as first documented by Cornelius Celsius during the Roman Empire, are redness, swelling, pain, and local heat. A fifth sign, loss of function, may also accompany inflammation. The formation of pus is not considered one of these cardinal signs. Pus formation is the result of the accumulation of dead leukocytes and is a secondary consequence that can occur during the inflammatory process. Therefore, the correct answer to the question 'Which of the following is NOT a cardinal sign of inflammation?' is D. pus formation.