Concept: This question tests your knowledge of floral formulas and their association with specific plant families or genera, particularly focusing on the Solanaceae family.

Why (A) Petunia is correct: The given floral formula is $\oplus {\text{ K}}_{(5)}{\text{ C}}_{(5)}{\text{ A}}_5{\underline{\text{G}}}_{(2)}$. This formula represents a flower that is actinomorphic (radial symmetry, $\oplus$), has five fused sepals (calyx, ${\text{K}}_{(5)}$), five fused petals (corolla, ${\text{C}}_{(5)}$), five free stamens (androecium, ${\text{A}}_5$), and a superior ovary with two fused carpels (gynoecium, ${\underline{\text{G}}}_{(2)}$). This is the characteristic floral formula for the family Solanaceae, to which Petunia belongs. The stamens are typically epipetalous (attached to petals) in Solanaceae, which is implied but not explicitly shown in this simplified formula.

Why other options are wrong:

• (B) Brassica: Belongs to Brassicaceae (Cruciferae), which has a formula like $\oplus {\text{ K}}_{2+2}{\text{ C}}_4{\text{ A}}_{2+4}{\underline{\text{G}}}_{(2)}$.
• (C) Allium: Belongs to Liliaceae, which has a formula like $\text{Br}{\text{ P}}_{3+3}{\text{ A}}_{3+3}{\underline{\text{G}}}_{(3)}$ (or ${\text{P}}_{(6)}$).
• (D) Sesbania: Belongs to Fabaceae (Papilionaceae), which has a zygomorphic flower and a formula like .

Common Mistake: Students often confuse the number of parts and whether they are fused or free, especially for calyx and corolla, and the position of the ovary (superior vs. inferior).

NEET Tip / Mnemonic: Remember the key features of major families: Solanaceae (potato family) has ${\text{K}}_{(5)}{\text{ C}}_{(5)}{\text{ A}}_5{\underline{\text{G}}}_{(2)}$ and often epipetalous stamens. Fabaceae (pea family) is zygomorphic with a distinct corolla (papilionaceous). Liliaceae (lily family) has perianth (P) instead of separate K and C.

Correct Answer: (A)