Originally Posted by invisibleman

people in this forum are making mistake about the questions answer,. spiral galaxy is not even a galaxy ,it is just a kind of galaxy ,it can be any galaxy , milky way and Andromeda both are spiral galaxies , in those options given in the question ,Andromeda is the correct answer , im surprised to see the people and SPSC ,all dont even search in the Google for it, it is clearly written, even a child can understand .

commercial aircrafts are designed to fly blow 12km, not above that , its fuselage is not designed to go above 12km, they fly in troposphere not in stratosphere,there are other reasons too. search in Google, don't even read, it is depicted in pictures and diagrams.