To develop this problem we will apply the concepts related to the kinematic equations of motion, specifically that of acceleration. Acceleration can be defined as the change of speed in an instant of time, mathematically this is

If a mobile is decreasing its speed (it is slowing down), then its acceleration is in the opposite direction to the movement. This would imply that the acceleration vector is opposite to the velocity vector.
Therefore the correct answer is B.
Explanation:
It is given that,
When a high-energy proton or pion traveling near the speed of light collides with a nucleus, 
Speed of light, 
Let t is the time interval required for the strong interaction to occur. The speed is given by :




So, the time interval required for the strong interaction to occur is
. Hence, this is the required solution.
Idk its really weird because the ridges are making the quarter stand and therefore able to roll
Quoting from the article itself:
"Since it is above Earth's atmosphere, it gives us clearer pictures of space than telescopes on Earth can."