The Centre has received a letter from Delhi Lt Governor Najeeb Jung "on options" and has asked him how long will it take for AAP leader Arvind Kejriwal to decide on government formation, Home Minister Sushilkumar Shinde said Thursday."We have received a letter from LG on options. We are asking how long will it take Kejriwal to decide. We have to give them five days," Shinde told reporters here.On Friday last, Kejriwal sought 10 days from Delhi Lt Governor Najeeb Jung to decide on the issue of government formation. He then sought public opinion on whether or not his party should form a government with Congress support.The Congress, with eight members in the 70-member assembly, has given unconditional support to the Aam Admi Party (AAP) which won 28 seats in the Dec 4 assembly poll.The BJP -- with 31 seats the single-largest party -- has refused to form a government."The Congress has given unconditional support so government has to be formed," said Shinde and added: "It takes time to form government."Shinde pointed out that the people of Delhi have not given a complete mandate and the BJP is unable to form the government.