For this case we have the following statement:
When Juan was ___________ to the actor, another reporter asked him a question.
We must fill in the blank with the correct verb
The correct verb conjugated in continuous past is:
Juan was interviewing
We have then:
When Juan was interviewing the actor, another reporter asked him a question.
The translation of the sentence in English is:
Cuando Juan estaba entrevistando al actor, otro reportero le hizo una pregunta.
Answer:
C. entrevistando