Read the passage given below and answer the question: Perhaps the worst of the ordeals was to be shut in a darkened room for long, uncertain periods, in solitary confinement and complete silence. Gagarin himself described the experience." Quote,"“There was no sound, not even the slightest rustle. No movement of the air—nothing. It was uncanny, unnerving.”" "He would shut his eyes and imagine himself in a space-cabin in orbit, looking at the world passing beneath him; or sometimes he would recite half-remembered poetry to himself." "Then, came parachute training. Gagarin made forty parachute jumps of gradually increasing difficulty." "One of the most interesting of the training experiments was the method of providing experience of weightlessness. In the early stages the express lift of the great Moscow University building was used. From the twenty-eighth floor to the bottom allowed a drop of 500 feet. At a certain high speed the passenger would find himself suspended between the floor and ceiling of the lift without support. This was a convenient and inexpensive way of reproducing ‘zero gravity’." "Special air brakes prevented the lift from crashing as it reached the bottom." "On the morning of April 12, Gagarin rose at 5.30. He was zipped into his complicated space-suit, on top of which went a pale blue fire suit, and finally an orange one. Then an Air Force bus drove him to the launching site in company with various helpers. The gantry lift took him up 100 feet, to the nose of the rocket, and he entered the cabin (named Vostok) with a wave to those below." ... and he entered the cabin' The underlined is a/an