RJD President Lalu Prasad today said Prime Minister Narendra Modi should either reply about the allegation of corruption leveled by Congress Vice President Rahul Gandhi or file a defamation case suit against him in Supreme Court. <br/><br/>Addressing Mahadharna against demonetisation at Patna, Mr. Prasad said allegation by Mr Gandhi is serious in nature. He said, RJD will try its best to bring all opposition parties under one umbrella over the issue of demonetisation. Alliance partners of ruling Nitish Kumar-led grand alliance, JD(U) and Congress did not participate in RJD dharna.