Read the conflict of a story.

Caroline and Rachel are sisters. Their mother announces that one of them will have to babysit their little brother on Saturday night. Both girls already have other plans with their friends and do not want to look after their little brother.

Which dialogue most effectively develops the conflict?

"I guess I should babysit," Caroline admitted, "because you can't change your plans as easily."
"If you think I'm babysitting, you've got another thing coming!" Rachel hissed at her younger sister.
"I'll babysit this time," Caroline said, "if you'll promise to watch him the next time."
"You probably think I should babysit because I'm older, right?" Rachel asked.