Herbicides are chemicals which control

Options

A. Insects
B. Fungi
C. Weeds
D. Nematodes.

Answer

### Step-by-Step Solution:

1. **Understanding Herbicides**: Herbicides are specialized chemicals used in agriculture and gardening to control unwanted plants, commonly referred to as weeds.

2. **Identifying Other Pesticides**: It's important to differentiate herbicides from other types of pesticides:
- **Insecticides**: Chemicals that control insects.
- **Fungicides**: Chemicals that control fungi.
- **Nematicides**: Chemicals that control nematodes (a type of roundworm).

3. **Definition of Weeds**: Weeds are defined as unwanted plants that compete with cultivated plants for resources such as nutrients, water, and sunlight.

4. **Example of Herbicide**: An example of a commonly used herbicide is 2,4-D, which is effective in controlling a variety of broadleaf weeds.

5. **Conclusion**: Based on the definitions and examples provided, the correct answer to the question "Herbicides are chemicals which control" is option C: **weeds**.