The correct line of code for strictly validating the request parameter value before processing it for execution is option B. This code snippet uses a regular expression to ensure that the CatId parameter only contains alphanumeric characters, which is a common validation technique to prevent SQL injection and other forms of attacks. The Pattern.compile("[a-zA-Z0-9]*$") creates a pattern that matches a string of zero or more alphanumeric characters. The matcher method is then used to match the pattern against the CatId parameter obtained from the request. If the parameter matches the pattern, m.matches() returns true, indicating that the parameter is valid.

References: The answer provided is in accordance with the best practices for input validation as outlined in the EC-Council’s Certified Application Security Engineer (CASE) JAVA training and certification program. The program emphasizes secure coding practices, including input validation to protect against common security threats such as SQL injection. For further details, please refer to the official EC-Council CASE JAVA course materials and study guides12.