Concept:Some plants can reproduce asexually using modified leaves that generate new plantlets.Explanation:In Bryophyllum, small adventitious buds develop along the leaf margins.When these leaves fall onto moist soil, the buds grow into independent new plants.Therefore, Bryophyllum is the well-known plant that undergoes vegetative propagation through leaves.Hibiscus mainly propagates by stem cuttings, Crotalaria reproduces by seeds, and Spirogyra reproduces by fragmentation.Answer:B. Bryophyllum