The sentence C shows correct capitalization for the proper name Natalie andthe adjective all-Amecican. The definition of the adjective all-American, in this case, is an amateur sports person from the US who is considered to be one of the best amateurs in their sport. It also means having the values that are typical of the US, or made up of the best American things or people.
The detail that helps you illustrate the idea? is that the only question? I can answer that is there anything else you need me to answer in the paragraph?