The question is about the breed of goat in India that produces the highest amount of milk. Let`s go through the options:

Option 1, Barbari, is a breed of small domestic goat generally kept for meat production, so their milk yield is typically not as high as others.

Option 2, Jamnapari, is the correct answer. This breed is known for both high meat and milk production. They are considered one of the largest and most productive breeds of goats in India.

Option 3, Black Bengal, is primarily kept for meat and hide production, they are not known for high milk yield.

Option 4, Beetal, is often used for both milk and meat production, but they are generally not as productive as Jamnapari when it comes to milk production.

So, the breed of goat in India that produces the most milk is indeed Jamnapari.