The most reliable evidence of the effectiveness of security controls implemented for a web application is penetration testing. Penetration testing is a process that simulates an attack on the web application by exploiting its vulnerabilities, using the same tools and techniques as real attackers. Penetration testing helps to evaluate the effectiveness of security controls, because it helps to verify that the security controls can prevent, detect, or mitigate the attack, and to measure the impact and severity of the attack. Penetration testing also helps to identify and address any weaknesses or gaps in the security controls, and to provide recommendations andsolutions for improving the security of the web application. The other options are not as reliable as penetration testing, although they may provide some evidence of the effectiveness of security controls. IT general controls audit, vulnerability assessment, and fault tree analysis are all examples of analytical or evaluative methods, which may help to assess or estimate the effectiveness of security controls, but they do not necessarily test or measure the effectiveness of security controls in a realistic scenario. References = 10