Answer: B) Chief of State
There is no official government role such as "party chief." If a governor is serving as host at a formal ceremony, he is doing so in his official role as Chief of State.
"Chief Legislature" is not a thing. And if it were, it would not apply to the governor, because he heads the executive branch, not the legislative branch.
"Commander-in-Chief" refers to a head of state's role in charge of the military. Within a state, that would refer to the governor's role in charge of National Guard troops within a state, which he can call upon to help in a domestic crisis within that state.