The underlined parts that need correction are:

1. For the sentence "You will become unhealthy if you eat too many **snack**," the correction is underlined under **A**: "snack" should be "snacks," so circle **A**.

2. For the sentence "Fruit and vegetables have all the vitamins **to protect** your body **with** diseases," the correction involves the phrase **D**: "with" should be changed to "from," so circle **D**.

So the corrections are:
- A: "snack" -> "snacks"
- D: "with" -> "from"