See image — Isomerism and Stereochemistry Chemistry Question

💡 Solution & Explanation

**Identifying Stereogenic Centers:** Examine the structure of 4-hydroxyproline for chiral centers (atoms bonded to 4 different groups): 1. **Carbon with $-OH$ and $-H$ (left side):** Bonded to $H$, $OH$, $CH_2$ (ring), and $CH$ (ring carbon bearing $COO^-$) → **Stereogenic center** 2. **Carbon with $-COO^-$ and $-H$ (right side):** Bonded to $H$, $COO^-$, $CH_2$ (ring), and $N^+H_3$ → **Stereogenic center** **Calculating Maximum Optically Active Isomers:** With **2 stereogenic centers**, the maximum number of stereoisomers is: $$2^n = 2^2 = 4$$ These are: - $(2R, 4R)$-4-hydroxyproline - $(2R, 4S)$-4-hydroxyproline - $(2S, 4R)$-4-hydroxyproline - $(2S, 4S)$-4-hydroxyproline All four are optically active (non-superimposable on their mirror images). **Answer: (B) 4**