The correct answer is: A. PSRQ
The sentence is about what would happen if the parachutes had failed to open. The first step would be for the pilot to pull a lever to provide an emergency ejection. This would cause the whole of his couch to be fired from the cabin. Once the couch was clear of the plane, special parachutes would unfold to bring the pilot down safely.
Option A, PSRQ, is the only option that follows this sequence of events. Option B, QPSR, is incorrect because it puts the step of pulling the lever after the step of the couch being fired from the cabin. Option C, RSQP, is incorrect because it puts the step of the special parachutes unfolding after the step of the couch being fired from the cabin. Option D, SQPR, is incorrect because it puts the step of the special parachutes unfolding before the step of the couch being fired from the cabin.