The correct answer is C. Voluntarily acquired citizenship of another country.
A person who has voluntarily acquired citizenship of another country is not a citizen of India. This is because, according to the Citizenship Act, 1955, a person can only be a citizen of India if he or she is born in India or if he or she has been naturalized as an Indian citizen. If a person has voluntarily acquired citizenship of another country, then he or she has renounced his or her Indian citizenship.
The other options are not correct because they do not necessarily mean that a person has renounced his or her Indian citizenship. For example, a person who has lived in a foreign country for more than five years may still be a citizen of India if he or she has not renounced his or her Indian citizenship. Similarly, a person who has been convicted by a foreign court of law may still be a citizen of India if he or she has not renounced his or her Indian citizenship. Finally, a person who has accepted employment in another country may still be a citizen of India if he or she has not renounced his or her Indian citizenship.
In conclusion, the correct answer is C. Voluntarily acquired citizenship of another country.