Which scenario best describes an inapppropriate tone, style, and/or voice in writing?

A story written for first-graders that uses simple vocabulary and bright, colorful pictures

A humorous story written in a personal diary that includes casual language and a joking, playful tone

A book review for language arts that uses very simple vocabulary

An e-mail to a friend that uses texting abbreviations such as idk, lol, and c-ya