Read the passage carefully and choose the correct answer

Herbal Medicine

Everyone wants to be healthy. People see doctors. They take pills to stay healthy. However, plants have been used to heal for thousands of years. More and more people are trying herbs to stay healthy. Plants used to heal are called “herbal medicine". There are many plants used In herbal medicine. Each plant is used In a certain way. Herbal medicine works more slowly than most pills. Many people think plants are gentle on the body. There are a lot of examples of helpful plants. Ginger can help your body. Eating ginger often may help you stay healthy. Another helpful plant is parsley. It can stop bad breath. Herbs may be gentler than some pills. However, this does not mean that anyone can take them in any way. You should always be careful. Some herbs can be harmful, too. Too much rosemary can be very bad for your stomach. It can make you sick. Foxglove is a very pretty flower. It also has poison in it. Nevertheless, if you are afraid of using herbs, you may be surprised. You have probably already used  some kind of herbal medicine. Coffee, garlic, ginseng and peppermint are all used in herbal medicine. Herbal medicine is becoming popular again, as people become more interested in their health.

How long have people used plants to cure?

• A. 
  for centuries
• B. 
  for years
• C. 
  for decades
• D. 
  for millenniums