Answer:
Kayla is correct The center is a fixed point in the middle of the sphere
Step-by-step explanation:
In mathematics we have certain habit of rules for notation of points, coordinates, segments, angles and so on.
Usually we denote points, by letters even more we denote with the first letter of the object we are denoting
Occasionally, we also denote segments as radius in a circle and in a sphere, with letters, that is r stands for radius, h stands for height, in most cases we denote point for capital letters ( in a segment)
When we denote radius, with small letter it should be placed at the center or over the segment we are traying to denote.
For points we only need to place the letter close to the to the point we want to denote.
Therefore Kayla is correct when says that c stand for " the center of the sphere"