Answer: had been hoping
Explanation: The past perfect progressive is used when the speaker connects two events in the past. The perfect indicates the cause / reason of an action. For example, The British government had been hoping to make the colonists trade exclusively with England, which put pressure on the tradesmen. If we ask: why were the tradesmen under pressure? The answer will require the use of the perfect: Because the British government had been..... Then, the progressive is used to show emphasis since the verb to hope is rarely used in the progressive.
The structure of the past perfect progressive is : had (auxiliary) + been ( paste participle of to be) + the main verb in the present participle ( hoping)