Site of photosynthesis.

**The reasoning** Photosynthesis is the process where plants convert light energy into chemical energy (glucose). This happens in the **chloroplast** because it contains **chlorophyll** — the green pigment that traps sunlight. Think of chloroplasts as the "solar panels" of the cell. Inside them, light reactions occur in the thylakoids and the Calvin cycle happens in the stroma, both producing the food plants need. **Why the wrong options tempt you** - **Nucleus** — You might think "command center = where everything happens," but the nucleus only stores DNA and controls activities; it doesn't do photosynthesis. - **Ribosome** — This makes proteins, not food from sunlight. Easy mix-up if you're rushing. - **Mitochondrion** — The trickiest trap! Mitochondria produce energy through **respiration** (breaking down glucose), which is basically the *opposite* of photosynthesis. Both deal with energy, but remember: mitochondria *release* energy, chloroplasts *capture* it. **Quick takeaway** **Chloroplasts capture light to MAKE food; mitochondria BREAK food to release energy** — one builds, one burns!