The correct option is A was given to them
Option A is correct as the context refers to the action is the passive voice. In such cases, we use theindirect object as the subject of a passive verb. So, ''was given" is used because when verbs have two objects, either object can be the theme or subject of the passive structure, depending on what we want to focus on. Here, we are focusing on 'the workers', so 'was given to them' addresses the 'workers' as the subject and uses the preposition "to" correctly.
Option B is incorrect as "gave them" indicates that 'rise' is the subject.
Option C is incorrect as the usage of the preposition 'for' here is incorrect as it is used as a function word to indicate purpose. Here, "to" is correct as it indicates direction of the action.
Option D is incorrect as the use of perfect continuous 'had been' is incorrectly used in this context.
Thus, option A is correct.