India’s government has asked Rahul Gandhi, the president of the main opposition Congress party, to respond to a complaint by a lawmaker from Prime Minister Narendra Modi’s party accusing him of holding dual British citizenship against Indian law. Gandhi, the scion of the Nehru-Gandhi dynasty that has dominated Indian politics for much of its history since independence from Britain in 1947, is the main challenger to Modi in the 39-day general election that began on April 11. Results will be known on May 23.