Make Me A Star Productions runs an annual talent competition for aspiring amateur singers.

Four business rules have been identified:
1) A contestant is allowed to sing 1 or 2 songs in a performance.
2) An audition may be attended by up to 50 contestants.
3) A contestant is always given an audition.
4) A song can only be used in one performance.
Which of these business rule(s) can be found to be correctly represented in the class diagram?