Explanation:

- Methanoic acid (Option 3): Also known as formic acid, is found in ant venom. It's responsible for the painful sensation and irritation from an ant sting.

- Lactic acid (Option 1): This acid is produced in muscle cells during strenuous activity. It's not associated with ant stings.

- Citric acid (Option 2): Commonly found in citrus fruits like lemons and oranges. It doesn't relate to ant venom.

- Oxalic acid (Option 4): Found in some plants, like spinach and rhubarb leaves. It's not present in ant venom.