USCIS did the right thing, you didn't meet the requirements. You need to observe all the laws as other future citizens do, as opposed to live in India and expect USCIS to honor you with US citizenship. You even had the gall to travel to India while your case was pending, what a man....lol!!! I mean, if you didn't show the ballz of steel to the IO by asking him such a ridiculous question, then I don't know what more other reason USCIS needed to give you. USCIS has guidelines which people ought to observe, but you didn't and you should start from scratch and calculate how you plan to meet the physical presence test and residence requirements. Rarely does USCIS send certified mail, but they wanted to clearly nail you azz on the wall....lol!!