A security team is reviewing the findings in a report that was delivered after a third party performed a penetration test. One of the findings indicated that a web application form field is vulnerable to cross-site scripting. Which of the following application security techniques should the security analyst recommend the developer implement to prevent this vulnerability?

Input validation is crucial for preventing cross-site scripting (XSS) because it ensures that data entered into a web application form field conforms to expected formats and types, sanitizing or rejecting malicious input. This stops attackers from injecting client-side scripts into web pages viewed by other users. Secure cookies enhance cookie security but don't prevent XSS itself. Version control manages code changes but doesn't directly address application vulnerabilities. Code signing verifies the authenticity and integrity of software but is unrelated to preventing XSS in web forms.