Dr Bradbury tries to find out the most popular snack amongst chocolate, biscuit, yoghurt and sweets. She surveyed all the students, and found out the following:

• Everyone who liked chocolate only liked chocolate.
• No one liked biscuits, yoghurt and sweets.
• There were more people who liked both sweets and yoghurt than both biscuit and yoghurt.
• There were more people who liked both biscuits and yoghurt than sweets and biscuit.
• There was the least number of people who only liked one snack.