Step 1: Understanding PMNL.
PMNL stands for Polymorphonuclear leukocytes, which are a type of white blood cell characterized by a nucleus with multiple lobes.
Step 2: Role of neutrophils.
Neutrophils are the most abundant PMNLs and play a major role in the innate immune system by engulfing pathogens through phagocytosis.
Step 3: Elimination of wrong options.
(1) Lymphocytes: Mononuclear, not PMNL.
(2) Monocytes: Also mononuclear, not PMNL.
(3) Neutrophils: Correct, they are polymorphonuclear.
(4) Platelets: Not cells but fragments, hence not PMNL.
Step 4: Conclusion.
Thus, the correct answer is (3) Neutrophil.