Answer:
I'm almost positive that's its C but if they already paid then D
Because it is flexible. Think about it; the ribs protect both the lungs and the heart. If the ribs were solid bone all the way around then unless you constantly break your ribs you wouldn't be able to expand the cheat to breath. Additionally your lungs would constrict the heart to a degree that it would function properly.
Answer:
The skills you would require to become an advanced martial artiest would be,
you would need to have peace and know how to keep your temper in check.
you would need discipline and high confidence along with a good amount of focus lots of clear goals and the most important one you need respect for not only you but also for others.
you need self in forced skills.
Answer:
Well 13 is a prime number so is that even possible?
It means 50% more in the designed projects