Imagine you are reading a story about a boy who rescues a puppy from a dark well. The story begins by describing how the boy's cousin once rescued him. As the story develops, you read how the boy volunteers at an animal shelter. You also learn that he plays with dogs that are waiting to find homes. What was the author's purpose of including the bolded sentence description?

The purpose is to provide an anecdote to introduce the boy to readers.
The purpose is to present an example of his willingness to help others.
The purpose is to describe the reasons for his actions.
The purpose is to add details about how he volunteers.