The Seventh Schedule to the Constitution of India divides legislative subjects into the Union List, the State List, and the Concurrent List. Any subject that does not fit into the State List or the Concurrent List is a residuary subject, and Article 248 specifically tells us who may legislate on it.
Since Article 248 explicitly assigns the residuary legislative field to Parliament, and no other authority listed has this power, Parliament is the correct answer.
Hence, the correct answer is The Parliament.