If you need to find the tense of the verb had been going, then the correct answer is C. past perfect progressive.
This tense is formed in the following way: past perfect of the verb to be (= had been) + perfect participle of the verb you need (it can be found in the third column of irregular verbs, or when it comes to regular verbs, you just add -d/-ed to the base of the verb).
Past progressive would be was going, present progressive would be is going, and present perfect progressive would be has been going.