• Entomopathogenic Nematodes (EPN) and Symbiotic Bacteria:
• Pair-by-Pair Matching:
• Steinernema carpocapsae $\rightarrow$ (IV) Xenorhabdus nematophila: Specific mutualistic bacterium carried in the specialized intestinal bacterial vesicle of infective juveniles ($IJs$).
• Steinernema feltiae $\rightarrow$ (II) Xenorhabdus bovienii: Specific symbiont providing toxin release and insecticidal septicaemia.
• Steinernema glaseri $\rightarrow$ (III) Xenorhabdus poinarii: Symbiont adapted to scarab beetle hosts.
• Heterorhabditis sp. $\rightarrow$ (I) Photorhabdus luminescens: Bioluminescent symbiotic bacterium that releases insecticidal complex (Tc toxins) and causes insect cadavers to glow in the dark.
• Correct Choice: Option 2 maps (A)-(IV), (B)-(II), (C)-(III), (D)-(I).

Correct option: (2) (A) - (IV), (B) - (I), (C) - (IN), (B) - (1)