Explain how internal migration contributes to the decline of indigenous language

Due to decrease in the population of people who speaks indigenous language.

Explanation:

Internal migration greatly contributes to the decline of indigenous language because the people who speak the indigenous language migrated to other regions and there are very less number of people who speak that indigenous language so we can say that Internal migration is responsible for the decrease of indigenous language. If we have to promote indigenous language so we have to reduce internal migration of people.

the answer is the last option or letter d)