Final answer:
The correct sentence is option b, since it properly uses lowercase after the dialogue tag and places quotation marks correctly. It adheres to the standard rules of punctuating dialogue in English writing.
Step-by-step explanation:
The correct sentence among the options given is: b. "Why do you never listen," she asked, "when I am speaking?"
The reason this sentence is correct is because in dialogue tags that break up a sentence, the first part ends with a comma inside the quotation marks, and 'she asked' is in lowercase. The second part of the sentence begins with a lowercase letter unless it’s a proper noun or the start of a new sentence. In this case, 'when' is not a proper noun nor the start of a new sentence, so it should remain in lowercase after the comma and outside the quotation marks. Option 'a' incorrectly capitalizes 'when', option 'c' incorrectly capitalizes 'She', and option 'd' is missing the closing quotation mark after 'listen.'.