The term vulnerability describes the issue that Adam discovered.
b. vulnerability
Step-by-step explanation:
SQL injection attack is an attack in which an external party can execute SQL commands on the database that serves as a back-end for a particular website. The SQL commands can be used to modify the contents of the website, modify the records, delete the records, and retrieve confidential information as well.
As Adam believes that the code has an issue that allows a SQL injection attack, the term that best describes the issue that he discovered is vulnerability. The website is vulnerable since the code does not have a proper procedure to tackle a situation of SQL injection attack.