Which state has the oldest flag in the world?

A. USA
B. Denmark
C. Japan
D. China

The oldest flag in the world

Denmark has the oldest flag in the world. The oldest used national flag is of Denmark state. The current design of a white Scandinavian cross on a red background was adopted in 1625 and its square shape in 1748.

Denmark is a  constitutional monarchy in northern Europe; consists of the mainland of Jutland and many islands between the North Sea and the Baltic Sea. In Denmark, its flag is known as the ‘Dannebrog’ or ‘Danish cloth’.