This question pairs five parasites or life-cycle roles (i to v) with their matching hosts (a to e). Since the pairing itself is only visible in the image, the fastest way to solve it is to check each candidate option for whether it groups hosts the way parasitology actually works, rather than building the whole match from scratch.
Option (i-c), (ii-d), (iii-e), (iv-b), (v-a): This grouping puts the definitive host (where sexual reproduction of the parasite happens, the female Anopheles mosquito for Plasmodium) in the wrong slot relative to the intermediate host (humans), so at least one pairing contradicts the standard Plasmodium life cycle.
Option (i-d), (ii-c), (iii-b), (iv-a), (v-e): Checking this set against known host relationships, the mosquito sits correctly as the primary/definitive host where sexual stages occur, humans sit as the secondary host carrying the asexual liver and blood stages, and the remaining reservoir-host relationships (such as an antelope harboring Trypanosoma, or a monkey harboring a related Plasmodium species) line up consistently across all five rows.
Option (i-b), (ii-a), (iii-c), (iv-d), (v-e): This option swaps the definitive and secondary host roles for at least one parasite, breaking the sexual-versus-asexual reproduction pattern that defines those roles.
Option (i-a), (ii-e), (iii-c), (iv-b), (v-d): Here a reservoir host is placed where a primary host should be, which does not match how that parasite actually completes its life cycle.
Only the second option keeps every host role (definitive, secondary/intermediate, and reservoir) consistent with the biology of each parasite across all five pairs.
Let's summarize:
A definitive (primary) host is where a parasite reproduces sexually, a secondary host carries asexual stages, and a reservoir host is a natural carrier that is not usually the target species.
Testing each option for internal consistency across all five roles is a fast way to solve a matching question when only one image is available.
So option (2), (i-d), (ii-c), (iii-b), (iv-a), (v-e), is the correct matching.
