The Chairman initiated the proceedings with a brief speech.

Answer: Option C

Initiated : cause (a process or action) to begin.
Complicated : consisting of many interconnecting parts or elements; intricate.
Started : begin or be reckoned from a particular point in time or space; come into being.
Closed : not open.
Confused : (of a person) unable to think clearly; bewildered.

Antonym of Initiated is Closed