What does the OCL expression self.employee$->$exists$($p $|$ p$.$firstName $=$ 'John'$)$ check?

Question $23$Answer

a$.$

It checks if the first name of all employees is 'John'.

b$.$

It checks if there is at least one employee named 'John'.

c$.$

It checks if all employees are named 'John'.

d$.$

It checks if there are no employees named 'John'.