Step 1: Recall hallmark orders.
Lepidoptera — butterflies and moths (scaled wings).
Hemiptera — “true bugs,” piercing–sucking mouthparts (e.g., stink bugs).
Orthoptera — crickets, grasshoppers, katydids (hind-leg jumping; stridulation).
Coleoptera — beetles (elytra/hardened forewings).
Diptera — true flies (one pair of wings + halteres).
Step 2: Map animals to orders.
\[
\text{Moths}\to \text{Lepidoptera (iv)},\quad
\text{True bugs}\to \text{Hemiptera (i)},\quad
\text{Crickets}\to \text{Orthoptera (ii)},\quad
\text{Beetles}\to \text{Coleoptera (iii)}.
\]
This matches option (C).
Final Answer:
\[
\boxed{\text{(C) P–iv;\; Q–i;\; R–ii;\; S–iii}}
\]