Concept:
Different animal groups show characteristic body symmetry.
Step 1: Identify each symmetry.
\[
\text{Gastropods} \rightarrow \text{Asymmetrical}
\]
\[
\text{Cnidarians} \rightarrow \text{Biradial symmetry}
\]
\[
\text{Triploblastic animals} \rightarrow \text{Bilateral symmetry}
\]
\[
\text{Adult Echinoderms} \rightarrow \text{Secondary radial symmetry}
\]
Thus,
\[
A-IV,\quad B-I,\quad C-III,\quad D-II
\]
Hence option (C) is correct.