The underlined verb, call, in the following sentence is correct because it is in the present tense, and the story takes place in the present. Sighing, I call Mom from my cell as I turned the car around. "I'm going to be late," I said. "I'll tell you the story when I get there."

I am not quite sure what the question here is, but the stated claim is false, so I'm assuming it has something to do with its revision.

The word "as" here suggests that two actions happend at the same time (calling mum and turning the car around). This, on the other hand means that both these actions need to be expressed in the same tense.

Since the verb "turned" is in the past tense, that suggests that the verb "call" should also be, meaning that the correct answer is "called".

So, the claim is false, because the verb should be in the past tense because the action also takes place in the past