According to Verity, why is a knowledge of colour important?

D. It can help you to sell products.

Giải thích:

Thông tin: 'Our toothpaste is always white or blue or maybe red. It's never green. Why not? For some reason we think that blue and white is clean, while we think of green products as being a bit disgusting. It's the same for businesses. We respect a company which writes its name in blue or black, but we don't respect one that uses pink or orange. People who design new products can use these ideas to influence what we buy.'