Arrange the parts to form a meaningful sentence: P: international security, taking into account its national security interests and priorities / Q: India has participated actively in multilateral forums / R: relating to disarmament, non-proliferation and / S: in the international security arena

The complete sentence reads: 'India has participated actively in multilateral forums (Q) relating to disarmament, non-proliferation and (R) international security, taking into account its national security interests and priorities (P) in the international security arena (S).' Q starts with the subject and verb, R describes the forums, P expands further, and S completes with the location/arena. Hence, the correct sequence is QRPS.