A dance teacher is creating a set list for an upcoming dance recital. There must be five numbers, performed in sequence. The numbers can be solos, duets or trios, made up of eight students: Amy, Belle, Carrie, Dana, Linda, Monique, Nicole and Ona. Each student will perform only once and the set list must conform to the follwing conditions:
Amy and Ona must perform solo
Carrie cannot perform in the second number unless Belle performs in the fourth
Nicole and Linda must perform together
Ona must perform at some time before Dana
The first and fifth numbers must be solos
Which of the following must be true?