What do these two changes have in common? photosynthesis milk going sour Select all that apply. Both are only physical changes. Both are chemical changes. Both are caused by cooling. Both by heating.

Both **photosynthesis** and **milk going sour** involve chemical changes. Here's a breakdown of each option: 1. **Both are only physical changes.** - **Incorrect.** - **Photosynthesis** is a chemical process where plants convert carbon dioxide and water into glucose and oxygen using sunlight. - **Milk going sour** is a chemical change caused by bacteria converting lactose into lactic acid. 2. **Both are chemical changes.** - **Correct.** - Both processes involve the transformation of substances into different chemical compounds. 3. **Both are caused by cooling.** - **Incorrect.** - **Photosynthesis** is driven by sunlight (a form of energy), not cooling. - **Milk souring** can be influenced by temperature, but it's typically accelerated by warmth rather than cooling. 4. **Both by heating.** - **Incorrect.** - While **photosynthesis** relies on sunlight (which includes heat energy), it's primarily the light energy that drives the chemical reactions, not just heating. - **Milk souring** is accelerated by warmer temperatures, but heating alone doesn't cause the chemical changes; it's the bacterial activity facilitated by suitable temperatures. **Summary:** - **Both are chemical changes.**