The following are citizens of the Philippines:
(1) Those who were citizens of the Philippines at the time of the adoption of the Constitution of the Philippines;
(2) Those born in the Philippines of foreign parents who, before the adoption of said Constitution, had been elected to public office in the Philippines;
(3) Those whose fathers are citizens of the Philippines;
(4) Those whose mothers are citizens of the Philippines and, upon reaching the age of majority, elect Philippine citizenship;
(5) Those who are naturalized in accordance with law.