Right answer:
trabajan
Trabajan is the conjugation of the verb trabajar for the third person plural in the simple present tense. This tense is used to talk about habitual actions or routines. This tense is also used to describe things that happen now or in the near future. So Amanda and Cristina work in the exam right now, that is, in the present. Finally:
Amanda y Cristina trabajan en el examen
