Randy is, of course, right with his citation above.
Reality is that the borrower often ELECTS TO GO ALONG WITH THE SELLER'S CHOICE.
And therein lies the answer to your question.
The buyer is CHOSING the same title company as the seller suggested.
Whether that company is on your provider list or not is what determines whether it is a B or C item on the LE.
(fwiw, you never want to tell an examiner that the seller chose anything.
)