As light from a star races through our atmosphere, it bounces and bumps through the different layers, bending the light before you see it. Since the hot and cold layers of air keep moving, the bending of the light changes too, which causes the star's appearance to wobble or twinkle.
Answer:
The magnitude of B is 
Explanation:
we know that
The magnitude of Vector B is

where
x,y and z are the components of vector B
we have

substitute



Can you send a pic of the question
Answer:
The 3rd option
Explanation:
She slows down, stops at 4 seconds, then speeds back up