Line is defined as a
a. a geometric shape that is open and moves from one point to another.
b. a slowly curving path along a plane.
c. a path through space.
d. the distance or area between, around, above, below, and within objects.

okay i have so many questions. but the big one here is: um wt..f is this mess? ?

it's when something is going so fast it makes a loud noise, breaking the sound barrier, for example: a jet makes a loud noise, not only cause of the jet but because they reached a point where they went so fast that you can year the noise from various parts, kinda like a police car, lets say the car was going   so fast that you hear the siren of the cop car right next to you, but the car is probably a mile a way, it's cos the siren was next to you a few seconds if you understand me