Explanation:

Arunachal Pradesh is likely to become India’s prime producer of vanadium.

• Vanadium is a chemical element with the symbol V and atomic number 23. It is a hard, silvery-grey, malleable transition metal.
• The elemental metal is rarely found in nature. It is recovered as a by-product from the slag collected from the processing of vanadiferous magnetite ores (iron ore).
• Vanadium is a high-value metal used in strengthening steel and titanium.
• The largest deposits of vanadium of the world are in China, followed by Russia and South Africa.

Hence option 4th is correct.