I believe it is D. Earth spinning on it's axis.
Answer:
Probability of tunneling is 
Solution:
As per the question:
Velocity of the tennis ball, v = 120 mph = 54 m/s
Mass of the tennis ball, m = 100 g = 0.1 kg
Thickness of the tennis ball, t = 2.0 mm = 
Max velocity of the tennis ball,
= 89 m/s
Now,
The maximum kinetic energy of the tennis ball is given by:

Kinetic energy of the tennis ball, KE' = 
Now, the distance the ball can penetrate to is given by:


Thus



Now,
We can calculate the tunneling probability as:



Taking log on both the sides:


Answer: Rubidium has 5 orbits/shells/energy levels.
Explanation: It's electron configuration is as follows: 2-8-18-8-1.
-- The position of the sun was originally the primary influence in determining
when people went to sleep and when they woke up. Although it no longer
directly influences us, that pattern is so deeply ingrained in our make-up
that our behavior still largely coincides with the positions of the sun.
-- The position of the Moon was originally the primary influence in determining
the cycle of human female physiology. Although it no longer directly influences
us, that pattern is so deeply ingrained in human make-up that the female cycle
still largely coincides with the positions of the Moon.