Step 1: Match Fasciola larvae.
Fasciola (liver fluke) uses snail as intermediate host. Hence (i - c).
Step 2: Match Sacculina.
Sacculina is a parasitic crustacean found in crab (Carcinus maenas). Hence (ii - d).
Step 3: Match Plasmodium.
Plasmodium is transmitted by female Anopheles mosquito. Hence (iii - b).
Step 4: Match Wuchereria.
Wuchereria causes filariasis in humans. Hence (iv - a).
Step 5: Eliminate incorrect matches.
All other combinations do not correctly represent host-parasite relationships.
Step 6: Conclusion.
Thus, correct matching is (i - c), (ii - d), (iii - b), (iv - a).