The forearms and lower legs each contain two bones running roughly parallel to each other. In the forearms, these two bones are the radius and ulna, and in the lower legs, these two bones are the tibia (the shinbone) and fibula.
The radius corresponds to the tibia and the ulna to the fibula.
It's most likely "proteins"
I think the correct answer is A
Most of the particles would pass through with a few moving at small angles because the atom was a low-density, positive material with electrons in it.