Although the diagram is not provided, I have encountered it before. The region labelled "B" is a ring with two small particles on it. This ring is the electron cloud and is where the electrons move. Therefore, it is negatively charged.
A.
conserve energy
The smaller muscle mass of the sloth, means that it needs less energy to work, allowing it to be able to survive on a less diet.
Most of their muscles are concentrated in their upper body, allowing them to be efficient climbers but very slow on the ground.