The correct answer is D. revolution/danger.
A black flag is a flag that is predominantly black in color. It is often used as a symbol of revolution, danger, or mourning. In the 18th and 19th centuries, black flags were flown by pirates to indicate that they would give no quarter to their enemies. In the 20th century, black flags were used by various revolutionary groups, such as the Black Panthers and the Weather Underground. Today, black flags are sometimes flown by anti-government protesters and by groups that support violence.
The other options are incorrect. A truce is a temporary cessation of hostilities between two or more parties. Peace is a state of harmony and tranquility. A protest is an expression of disapproval or objection.