Which sentence uses the colon correctly?

1. ক
   I need three items: apples, oranges, and bananas.
   
2. খ
   I need: apples, oranges, and bananas.
   
3. গ
   I need three items, apples, oranges, and bananas.
   
4. ঘ
   I need three items; apples, oranges, and bananas.