Substitution effect: When the price of an item rises, consumers tend to replace the item that has become more expensive with other items in order to obtain the cheapest satisfaction. Which of the following are not part of the substitution effect? ['Coffee prices rise, tea drinkers increase.', 'A stock appreciates and many people compete for it.', 'Email is cheaper than sending by post, so more people use email.', 'The price of hemp raw materials in a textile mill has risen, and cheaper cotton is used for production.']