The correct answers are C) I was thinking about Cape Town when Sathima called. D) He's playing a song he learned from Max Roach. E) By the time the police arrived, the intruder had left.
The shift in verb tenses is acceptable in the following sentences:" I was thinking about Cape Town when Sathima called." "He's playing a song he learned from Max Roach." And "By the time the police arrived, the intruder had left."
We are referring to a grammar subject, tense shift. This means to change a verb tense to another. It could be from past to present in the same sentence or the same paragraph. What the author tries to do when using tense shift is to light up the moment of making it more vivid to improve its narrative.