The answer that correctly uses the colon is the last sentence. Normally a colon is meant to be used when it is showing a list of options, but the first and second sentence only have one sentence after that. A colon also can show reasons why a person does something, but for the third option, there's only one reason. In the last statement, the colon is used to break up the statement. It also shows that Harry has something in account for what he wants in his life. So, your answer option should be "D"
Hope this helps!
Singed, Liz
Minatozaki Sana was going to be staying at her widowed auntie's house. She was looking forward to it as the last time she saw her auntie was when she was a baby. The wheels practically slid on the path made of gravel, that's how freezing it was. Looking out the window, Sana thought to herself, "Will this rain ever stop?"
its not exactly 50 words
Definition.
A writer would BEST DEVELOP a paragraph using a DEFINITION when he wants to get at the meaning of an abstract concept.