Step 1 : Introduction to the question "Yemen's national flag has three horizontal bands of three different colours. Which of these is not a colour on the Yemen flag?"
...The flag of Yemen was first adopted on the 22nd of May 1990, which was the day that North Yemen and South Yemen joined to form one nation. The top third of the flag is red, the middle is white and the bottom is black. The red symbolises bloodshed of martyrs as well as representing unity, the white signifies a bright future and the black represents a dark past. The national motto is ""Allah, al-Watan, ath-Thawrah, al-Wahdah", which means "God, Country, Revolution, Unity". The national anthem is "United Republic".