What color do you like best? Do you like yellow, orange and red? If you do, you must be an optimist, a leader, or an active person who enjoys life, people and excitement. Do you prefer grey and blue? Then you are probably quiet, shy and you would rather follow than lead. If you love green, you are likely to be strong-minded and determined. You wish to succeed and want other people to see you are successful. At least this is what psychologists  tell us. They have been seriously studying the meaning of color preference, and the effects that colors have on human beings. They tell us that we don't choose our favorite color as we grow up. If you happen to love brown, you do so as soon as you open your eyes, or at least as soon as you could see clearly. Black is while light and bright colors make people not only happier but more active. A yellow room makes us feel more cheerful and more comfortable than a dark green one does, and a red dress adds warmth and cheer to sad winter days. It is a fact that factory workers work better, harder and have fewer accidents when their machines are painted orange rather than black or dark grey. Remember, then, that if you feel low, you can always brighten your day or your life with a few colorful things. Also remember that you will know your friends (and your enemies) better when you find out what colors they like and dislike. And don't forget that anyone can guess a lot about you when you choose a piece of handkerchief. 68. Why are machines painted orange in some factories, according to the passage?
Because workers tend to prefer orange to other colors. Because other colors are forbidden in factories. Because less accidents happen due to the introduction of orange machines. Because orange machines are easier to clean.