Aria and Camilla should consider trademark and copyright laws to protect their orchestral piece. However, since "copyright" is not one of the options provided in your prompt, the closest responses based on the provided choices would be trademark; patent.
Note: While "patent" generally applies to inventions and not musical works, "copyright" is what typically protects original works of authorship, including music. Nonetheless, from the options given, "trademark; patent" is the best fit, although it's important to clarify that copyright would be the most relevant law for their specific situation.