A、Mainly because of their cultural values. B、Mainly because of their personal experiences. C、Mainly because of their commercial

Why is pink or purple a colour for girls and blue or brown for boys?
    The answer depends largely on cultural values as well as personal experiences. To the Egyptians, green was a colour that represented the hope and joy of spring, while for Muslims, it means heaven. Red is a symbol of good luck in many cultures. In China, children are given money in a red envelope to bring good fortune in the New Year. For many nations, blue is a symbol of protection and religious beliefs. Greek people often wear a blue necklace hoping to protect themselves against evils.
    People’s choice of colours is also influenced by their bodies’ reactions toward them. Green is said to be the most restful colour. It has the ability to reduce pain and relax people both mentally and physically. People who work in green environment have been found to have fewer stomach aches.
    Red can cause a person’s blood pressure to rise and increase people’s appetites. Many decorators will include different shades of red in the restaurant. Similarly, many commercial websites will have a red "Buy Now" button because red is a colour that easily catches a person’s eye.
    Blue is another calming colour. Unlike red, blue can cause people to lose appetite. So if you want to eat less, some suggest that eating from blue plates can help.
    The next time you are deciding on what to wear or what colour to decorate your room, think about the colour carefully.
Questions 16 to 18 are based on the passage you have just heard.
16. Why do Muslims regard green as a symbol of heaven?
17. Why will many commercial websites have a red "Buy Now" button?
18. What colour might help lose weight according to the passage?