Which sentence is correct?
The movie *Horton Hears a Who!* starts at seven o'clock.
The movie *Horton Hears a who!* starts at seven o'clock.
The movie "Horton Hears a Who!" starts at seven o'clock.
The movie *Horton Hears a Who!* starts at seven o'clock.
The movie *Horton Hears a who!* starts at seven o'clock.
The movie "Horton Hears a Who!" starts at seven o'clock.