The response that best shows Joe is using a personal connection to understand August’s character is:
"I know how it feels to want to laugh and cry at once. When my family had my grandfather’s funeral, we were very sad. But still we laughed, remembering Grandpa’s funny jokes. I understand how August felt."
This response illustrates Joe’s understanding of the complex emotions that August is experiencing, using his own personal experience to relate to the feeling of having mixed emotions. By sharing a specific moment from his life, Joe demonstrates empathy and a deeper connection to August's character.