Chloroplasts reside in photosynthetic mesophyll cells of leaves

Steps:

• Examine typical leaf cross-section: upper epidermis, palisade mesophyll, spongy mesophyll, lower epidermis, vascular bundles.
• Chloroplasts enable photosynthesis, so they occur in cells exposed to light for CO2 absorption and sugar production.
• Palisade mesophyll (W) and spongy mesophyll (Z) are the primary photosynthetic layers with abundant chloroplasts.
• Epidermis (X) protects but lacks chloroplasts; vascular tissue (Y) transports but does not photosynthesize.

Why D is correct:

• Mesophyll cells (palisade and spongy) contain chloroplasts as per plant cell specialization for photosynthesis, defined by their role in light-dependent reactions.

Why the others are wrong:

• A: X (epidermis) lacks chloroplasts for protection, not photosynthesis.
• B: Y (vascular) transports water/nutrients without chloroplasts.
• C: X and Y both non-photosynthetic, no chloroplasts.

Final answer: D