Which one among the following is present in the nettle leaf hairs that

Which one among the following is present in the nettle leaf hairs that causes burning pain ?

Methanoic acid
Ethanoic acid
Benzoic acid
Acetic acid
This question was previously asked in
UPSC NDA-1 – 2024
Methanoic acid is present in nettle leaf hairs and causes a burning pain.
The stinging hairs (trichomes) of nettle plants contain several irritants, including histamine, acetylcholine, serotonin, and an acid. The primary acid responsible for the burning and stinging sensation is formic acid, also known by its IUPAC name, methanoic acid (HCOOH).
Ethanoic acid is acetic acid (CH₃COOH), found in vinegar. Benzoic acid (C₆H₅COOH) is an aromatic carboxylic acid. While other chemicals contribute, methanoic acid is the key acidic component causing the initial sting.