• Host-Nematode Associations:
• Pair-by-Pair Matching:
• Coconut $\rightarrow$ (II) Bursaphelenchus cocophilus: Red ring nematode, transmitted by palm weevils (Rhynchophorus palmarum), causing fatal red ring disease of coconut and oil palms.
• Barley $\rightarrow$ (I) Anguina radicicola: Root-gall nematode of grasses and barley, inducing distinct terminal root galls.
• Taro $\rightarrow$ (III) Hirschmanniella miticauda: Causes severe corm rot and black spongy rot of wetland taro (Colocasia esculenta).
• Walnut $\rightarrow$ (IV) Cacopaurus pestis: Sessile ectoparasite attacking Persian walnut trees, causing root decay and tree dieback.
• Correct Choice: Option 1 matches (A)-(II), (B)-(I), (C)-(III), (D)-(IV).

Correct option: (1) (A)- (H), (B)- (0), (C) = (il), (D) = (V)

• Comparative Histopathology of Banana Root Lesions:
• Helicotylenchus multicinctus (Spiral nematode): Semi-endoparasitic feeder that invades only the superficial layers of the root cortex, creating small, discrete, shallow necrotic spots ($\lt 2-3\text{ mm}$ deep).
• Radopholus similis (Burrowing nematode): Extensive migratory endoparasite that creates massive, continuous, deep reddish-brown to black necrotic cavities penetrating through the entire cortex to the stele, destroying structural support.
• Diagnostic Distinction: Lesions differ fundamentally in their size and depth within root tissues (Option 2).

Correct option: (2) Size and depth