It is the biggest election in history. Across India, from the Himalayan mountains to the Andaman Islands in the Bay of Bengal, the first wave of millions of citizens started casting ballots Thursday in a five-week-long vote to choose a new Parliament, which will select a prime minister. India is the world’s largest democracy, the most populous nation after China, and a pivotal geopolitical power. And it has never before held an election of this magnitude: 900 million eligible voters; at least 11 million poll workers; 2.3 million electronic voting machines; 2,000 political parties; and special trains, boats, helicopters and even elephants to transport voting equipment.