Which chemical (fumigant) was discovered as the first nematicide?

✅Explanation:
Carbon disulfide (CS2) was the first chemical discovered and used as a nematicide. In the mid-19th century, it was observed that CS2, when applied to soil, could control the grape phylloxera, a devastating aphid pest in vineyards. Further research revealed its effectiveness against nematodes as well.

📌Other Options Explanations:
(b) DD: Dichloropropene-Dichloropropane (DD) is a soil fumigant with nematicidal propertie.
(c) EDB: Ethylene dibromide (EDB) was another widely used nematicide.
(d) Methyl bromide: Methyl bromide is a broad-spectrum fumigant with nematicidal activity. Its use is also being phased out due to its ozone-depleting properties.