Final answer:
The nurses are participating in picketing outside the hospital to express their grievances and attract attention to their cause. The correct option is (a).
Step-by-step explanation:
The nurses are participating in picketing outside the hospital. Picketing is a form of protest where individuals or a group assemble outside a workplace to express their grievances and attract attention to their cause.
In this case, the nurses are protesting the use of foreign nurses and expressing their dissatisfaction with the hospital's decision to terminate some nurses.
They carry signs with messages asking potential patients to seek care elsewhere, which further highlights their protest.