D) "alphabetically by author's last name or by the title of the article (if author's name is unknown)"
Explanation:
Google says:
"Arrange entries in alphabetical order by the first term in each entry (the first author's last name or the title of the work when there is no author). "
The esophagus is the tube that connects the mouth to the stomach. Heartburn occurs. B. It has a bitter taste when some of the stomach juices flow backwards up the esophagus. To help relieve