The correct answer is B) Mayor...Chairman.
Although there is no one person in charge in commission-style city governments, there is one commissioner elected as Mayor or Chairman to preside over meetings.
Here we are talking about a specific form of local or municipal government in the United States. Here, the elected official works in what is known as a Commission that is manifested in a governing board with few members. One of the most notable characteristics of this form of government is that the Commission has no more than seven members and has the powers of an executive and of the legislative in the municipality.
That is why although there is no one person in charge in commission-style city governments, there is one commissioner elected as Mayor or Chairman to preside over meetings.