In most cases this means the country in which the applicant was born.
However, if a person was born in an ineligible country but his/her spouse was
born in an eligible country, such person can claim the spouse's country of birth
providing both the applicant and spouse are issued visas and
enter the U.S. simultaneously.
For example, you were born in United Kingdom (which is not an eligible country),
but your wife was born in Australia,
you may charge nativity to Australia because of your spouse.
Also, if a person was born in an ineligible
country, but neither of his/her parents was born there or resided there at the time
of the birth, such person may be able to claim nativity in one of the parent's country of birth.
For example, if you were born in India which is NOT an
eligible country, but your father was
born in Germany and your mother was born in France, you can claim Germany or France as your native
country for the purpose of this application.