The answer is: B
Explanation
The correct option is B: Mandatory.
Section 10 of CPC is a mandatory provision that prohibits the court from proceeding with the trial of any suit in which the matter in issue is directly or substantially the same with the previously instituted suit between the same parties, or between parties under whom they or any of them claim litigating under the same title, where such suit is pending in the same or any other court in India having jurisdiction to grant the relief claimed, or in any court beyond the limits of India established or continued by the Central Government and having like jurisdiction, or before the Supreme Court. The purpose of this section is to prevent multiplicity of suits, avoid conflicting decisions, and protect the parties from harassment. The section applies to the trial of the suit and not the institution, and it does not restrict the court from passing interim orders like injunction or stay. The section is based on the principle of res sub judice, which means a matter that is under consideration or trial by a court or judge. The section lays down certain conditions for the application of this principle, such as the identity of parties, the identity of matter in issue, the pendency of the previously instituted suit in a court of competent jurisdiction, and the possibility of granting the relief claimed in both the suits. If these conditions are satisfied, the court has no discretion but to stay the subsequent suit until the disposal of the earlier suit. The section is not merely a rule of procedure, but a matter of public policy and justice. Therefore, the provisions of section 10 of CPC are mandatory and not directory, none-mandatory, or discretionary.