Final answer:
The synonym for 'sovereign' from the provided options is 'independent', as it denotes freedom from external control and aligns with being supreme or having authority.
Step-by-step explanation:
The synonym for sovereign from the given options is independent. The word sovereign refers to having supreme authority or power and being free from external control. This idea aligns closely with the concept of being independent, which means not being influenced or controlled by others, and being self-sufficient. Options A, B, and C (dependent, submissive, subservient) all imply some form of reliance or subordination, which is opposite to the notion of a sovereign or independent entity.