The correct answer is (a) the Parliament.
The Code of Civil Procedure is a procedural law that governs the conduct of civil litigation in India. It is a central act, which means that it is enacted by the Parliament of India and applies to the whole country. The Parliament has the power to amend the Code of Civil Procedure, as it does with other central acts.
A High Court is a superior court of law in India. It has the power to interpret the Code of Civil Procedure, but it does not have the power to amend it. The Court hearing the suit is a lower court, and it has no power to amend the Code of Civil Procedure.
The parties to the suit are the plaintiff and the defendant. They are the individuals or entities who are involved in the litigation. They do not have the power to amend the Code of Civil Procedure.