The best answer from the choices provided would be:
b. charges of corruption and embezzlement
While the history of Philippine presidents includes instances of military coups d'état and the inability to put down internal rebellions, the most common reason for the replacement of recently elected presidents in the Philippines has been charges of corruption and embezzlement. Corruption has been a significant issue in Philippine politics, and allegations of corruption have led to the impeachment or forced resignation of several presidents in the past.