Answer:
Semicolon
Explanation:
Using adjunctive adverbs, like however, is helpful to link two independent clauses in order to create just one sentence. They are positioned between a semicolon (;) and a comma (,). The writer does this so as to simplify speech and get ideas across in a clearer way.
The two sentences which are linked in this opportunity are "Everyone knows he is the best cook" and "he refused to enter the contest".
