Final answer:
The four classic symptoms of inflammation are erythema, edema, pain, and heat. The correct answer to fill in the blank is 'heat', which is a local effect of increased blood flow and not a systemic effect like fever.
Step-by-step explanation:
The four classic symptoms of inflammation are erythema (redness), edema (swelling), pain, and heat. Erythema and edema result from increased blood flow to the affected tissue, which is a response of the innate immune system to infection or injury. Pain is caused by the stimulation of nerves in the area, and heat is the warmth felt at the site of inflammation due to the increased blood flow and cellular activity. Although fever can be a systemic sign of inflammation, it is not considered one of the local cardinal signs of inflammation. Therefore, the correct answer to fill in the blank for the classic symptoms of inflammation is 'heat'.