A、A warm colour is a colour that is often used in restaurants. B、A warm colour is a colour that gives off heat. C、A warm colour

Researchers do not know why people think some colours are warm and other colours are cool. However, almost everyone agrees that red, orange, and yellow are warm and that green, blue, and violet are cool. Perhaps warm colours remind people of warm days and cool colours remind them of cool days. Because in the north the sun is low during the winter, the sunlight appears quite blue. Because the sun is higher during the summer, the hot summer sunlight appears yellow.
    People associate colours with different holidays. For example, red is associated with Valentine’s Day. On February 14th, Americans send red hearts to people they love. People associate orange with Halloween in October and Thanksgiving Day in November. On October 31 st, many Americans put large orange pumpkins in their windows for Halloween. Many people wear green on St. Patrick’s Day, March 17th. Violet is a dignified colour which is associated with Easter. On Easter Sunday, people decorate baskets with purple ribbons.
    Many expressions in English use colours. These expressions show how people feel about the colours. For example, people associate red with a strong feeling like anger. When someone is very angry, people say that he or she sees red. Red is an active colour. A red-letter day is a lucky day. When criminals are caught in the middle of a crime, people say that they are caught red-handed. Green is the colour of grass and leaves. When someone grows plants well, people say he or she has green fingers. Blue is a sad, thoughtful colour. When someone is very sad, people say he or she is feeling blue. Blues is a kind of jazz that is usually very sad and slow.