Forceful expiration involves contraction of:
Pick C: Internal intercostals and abdominal muscles. Thinking about Cardiac Cycle and Regulation in a practical way — what the structure does, or what the process achieves — leads you here. Clinically and academically, the same logic shows up again and again: Internal intercostals and abdominal muscles is the option that correctly names the structure, process, or principle asked for in Cardiac Cycle and Regulation. Hence Internal intercostals and abdominal muscles is correct. Treat this as a building block for the rest of Cardiac Cycle and Regulation; neighbouring topics often reuse the same principle. Keep a one-line summary card for this idea and revisit it before the paper; short, repeated review beats long cramming sessions.
Ref: Animal physiology is Unit 7 of the CSIR NET Life Science Syllabus, covering core body systems. It accounts for roughly 10% of the total marks in Sections B and C.