Краткое пояснение:
The sentence describes an action that continued for a duration in the past ('for 3 years') before another past action ('before she decided'). The past perfect continuous tense ('had been making') is used to emphasize the duration of an action that happened before another past event.
Варианты ответа:
- a) Was making
- b) had been making
- c) had made
Ответ: b) had been making