Consider the following statements regarding Internal Migration in India:

I. According to the Office of the Registrar General & Census Commissioner, India, a person is considered a migrant only if the place of birth is different from the place of enumeration.

II. In India, rural-to-urban migration constitutes the largest share of total internal migration.

III. Marriage is the single largest reason for female internal migration in India.

IV. Interstate migration accounts for a larger share of internal migration than intrastate migration.

How many of the statements given above are correct?