Question ID:PT75 S3 Q17 Passage:Rocket engines are most effective when exhaust gases escape from their nozzles at the same pressure as the surrounding atmosphere. At low altitudes, where atmospheric pressure is high, this effect is best produced by a short nozzle, but when the rocket passes through the thin upper atmosphere, a long nozzle becomes more effective. Thus, to work most effectively throughout their ascents, all rockets must have both short nozzles and long nozzles on their engines. Stem:Which one of the following is an assumption the argument requires? Correct Answer Choice:BChoice A:Equipping a rocket's engines with both short and long nozzles is not significantly more difficult than equipping them with nozzles of equal lengths. Choice B:At some point during their ascents, all rockets will pass through the thin upper atmosphere. Choice C:A rocket with only short nozzles on its engines cannot reach high altitudes. Choice D:For a rocket to work effectively, its engines' exhaust gases must leave the nozzles at the same pressure as the surrounding atmosphere throughout the rocket's ascent. Choice E:For a rocket to work most effectively at both low and high atmospheric pressures, it must have at least one engine that has both a short nozzle and a long nozzle.