Answer:
Doctor, ace, connoisseur, virtuoso etc.
Step-by-step explanation:
Synonyms are those words that have the same meaning with another word. They are different in all aspects, be it the spelling or the word or sound, but have a similar meaning with numerous other words. They all have the same connotation for a given word.
The word specialist means someone who is an expert in a specific field of study or issue or topic. So, its synonyms can be a doctor, a consultant, virtuoso, an ace, professional, connoisseur etc among others. They all signify someone who is an expert in a particular field of study. And considering there are n given options, the best answers can be among the numerous examples given in earlier.