Step 1: Understanding the Concept
At a site of infection, neutrophils move in and engulf the invading microbes.
Step 2: What happens next
After engulfing, the neutrophils die. The dead cells collect together with the killed microbes and damaged tissue cells.
Step 3: Result
This creamy-yellow mass is called pus.
Final Answer:
Pus is a mixture of dead neutrophils, damaged tissues and dead microbes.
\[ \boxed{\text{(A) }\text{dead neutrophils, damaged tissues and dead microbes}} \]