Which one of the following is a modified stem ?

The correct answer is Potato. Potato tubers are swollen underground stems (modified stems) that arise from stolons or stem tissues and function in food storage; they bear “eyes” (axillary buds) from which new shoots develop, a clear stem characteristic [2]. By contrast, carrot is a modified taproot and sweet potato is a tuberous (storage) root — both are root modifications, not stems. Coconut represents a seed/fruit structure, not a modified stem. Because tubers regenerate whole plants via buds and have nodes/eyes like stems, potatoes are classified botanically as modified stems, whereas sweet potato and carrot are root modifications [1].

Sources

1. [1] https://verso.uidaho.edu/view/pdfCoverPage?instCode=01ALLIANCE_UID&filePid=13325578290001851&download=true
2. [2] Science , class X (NCERT 2025 ed.) > Chapter 7: How do Organisms Reproduce? > Activity 7.5 > p. 118