As part of the security assessment plan, the security professional has been asked to use a negative testing strategy on a new website. Which of the following actions would be performed?

A. Use a web scanner to scan for vulnerabilities within the website.
B. Perform a code review to ensure that the database references are properly addressed.
C. Establish a secure connection to the web server to validate that only the approved ports are open.
D. Enter only numbers in the web form and verify that the website prompts the user to enter a valid input.