To test your website for vulnerabilities, you type in a quotation mark (? for the username field.
After you click Ok, you receive the following error message window:
What can you infer from this error window?
Exhibit: 
A.
SQL injection is not possible
B.
SQL injection is possible
C.
The user for line 3306 in the SQL database has a weak password
D.
The quotation mark (? is a valid username