Manner of election of President

Which of the following provision of the Constitution of India need the ratification by the legislatures of not less than one half of the States to effect amendment? (a) The manner of election of the president of India (b) Extent of the executive power of the union and the States (c) Power of the Supreme Court and High Courts (d) Any of the Lists in the 7th Schedule

Who decides the disputes regarding election of President?