Final answer:
Carrie Underwood's album "Storyteller" was the one that dominated country music sales in 2015.
Step-by-step explanation:
The correct answer to the question about the album "Storyteller" dominating country music sales in 2015 is A) Carrie Underwood. Carrie Underwood is a renowned country music singer and Storyteller was her fifth studio album, released on October 23, 2015. The album was a commercial success, marking her continued prominence in the country music industry after her victory in American Idol.