Explanation:

Here's how it all breaks down:

- Option 1: Methanoic acid (also called formic acid) is the acid found in ant stings. This is what causes the burning and irritation when an ant bites you.

- Option 2: Oxalic acid shows up in plants like spinach and rhubarb. It’s not part of ant venom at all.

- Option 3: Lactic acid pops up in sour milk, yogurt, and in your muscles after a tough workout. It’s got nothing to do with ant stings.

- Option 4: Citric acid is the reason lemons and oranges taste sharp, but it’s not in ant venom.

So, you got it—ant stings owe their pain to methanoic acid.