Answer:
a) rebels
Step-by-step explanation:
Robert K Merton developed strain theory which states that a person feels strained when they are not able to achieve the goals that are set by society through culturally accepted means.
When people try to actively change the culturally accepted goals and means it is known as rebellion.
The Irish Republican Army (IRA) wanted to free from the rule of the British. Hence, they would be considered as rebels according to Robert K Merton.