Final answer:
In the context of "trouble" meaning annoyance or bother, the synonym that best matches is 'irritation'. It specifically conveys the sense of annoyance, closely aligning with the meaning of 'trouble'.
Step-by-step explanation:
Considering the context in which "trouble" is used, meaning annoyance or bother, the correct synonym is irritation. Options b) Irritation and c) Nuisance both work as synonyms in the broad sense, but irritation specifically conveys the sense of annoyance or bother, which aligns more closely with the meaning of "trouble" in this context.
The terms a) Tormentor and d) Disturbance do not fit as precisely; 'tormentor' suggests an agent causing distress, while 'disturbance' implies an interruption or commotion, which may not necessarily relate to annoyance.