Which of the following is an example of a zygomorphic flower?

The correct option is Pea.

Based on their symmetry, flowers are classified into three types:
1. Actinomorphic (Radial symmetry): These flowers can be divided into two equal radial halves by any vertical plane passing through the central axis. Examples include Datura, Chilli, and Petunia.
2. Zygomorphic (Bilateral symmetry): These flowers can be divided into two similar halves only along one specific vertical plane. Examples include Pea, Bean, Gulmohar, and Cassia.
3. Asymmetric (Irregular): These flowers cannot be divided into two similar halves by any vertical plane passing through the center (e.g., Canna).

Thus, among the options provided, Pea is the correct example of a zygomorphic flower.