Step 1: What is asked.
We need the country with which India signed a lithium exploration and mining deal.
Step 2: Why lithium.
Lithium is a key metal for electric vehicle batteries, so India wants a steady supply of it.
Step 3: India's effort.
India's company KABIL, which means Khanij Bidesh India Ltd, hunts for such minerals abroad.
Step 4: The partner.
India signed an agreement with Argentina, a country in the so called Lithium Triangle, to explore and mine lithium.
Step 5: Remove others.
Brazil, Australia, and Chile are not the partner in this particular deal.
Step 6: Conclusion.
So the lithium mining partner is Argentina.
Answer: Argentina