Web content accessibility guidelines (WCAG) are a set of standards that aim to make web content more accessible to people with disabilities, such as visual, auditory, cognitive, or motor impairments. While WCAG is a good practice for web development and usability, it is not directly related to web application security. WCAG does not address the common security risks that web applications face, such as injection, broken authentication, misconfiguration, or vulnerable components. Therefore, adhering to WCAG is not a method of securing web applications, unlike the other options.Reference:

4: OWASP Top 10, a standard awareness document for web application security, lists the most critical security risks to web applications and provides best practices to prevent or mitigate them.

5: SANS Institute, a leading provider of cybersecurity training and certification, offers a security checklist for web application technologies (SWAT) that covers best practices for error handling, data protection, configuration, authentication, session management, input and output handling, and access control.

6: Built In, a platform for tech professionals, provides 13 web application security best practices, such as using a web application firewall, keeping track of APIs, enforcing expected application behaviors, and following the OWASP Top 10.