To solve this problem, we need to identify which of the given options is an example of an actinomorphic flower.$\newline$Actinomorphic flowers are those that are radially symmetrical, meaning they can be divided into two equal halves through any plane that passes through the center.$\newline$Let's analyze each option:$\newline \bullet$Option 1: Pisum (Pea)$\newline$ - Pisum flowers are zygomorphic, meaning they have bilateral symmetry and can only be divided into two equal halves in one plane.$\newline \bullet$Option 2: Sesbania$\newline$ - Sesbania flowers are also zygomorphic, similar to Pisum, with bilateral symmetry.$\newline \bullet$Option 3: Datura$\newline$ - Datura flowers are actinomorphic, as they exhibit radial symmetry and can be divided into two equal halves through multiple planes.$\newline \bullet$Option 4: Cassia$\newline$ - Cassia flowers are zygomorphic, with bilateral symmetry.$\newline$Based on the analysis, the correct answer is Option 3: Datura, which is an example of an actinomorphic flower.