Which of the following can BEST prevent security flaws occurring in outsourced software development?

The best way to prevent security flaws occurring in outsourced software development is to establish contractual requirements for code quality that specify the security standards, guidelines, and best practices that the outsourced developers must follow. This way, the organization can ensure that the outsourced software meets the expected level of security and quality, and that any security flaws are detected and remediated before delivery. The other options are not as effective as contractual requirements for code quality, as they either do not address the security aspects of the software development (B and D), or do not prevent the security flaws from occurring in the first place ©. References: CISSP All-in-One Exam Guide, Eighth Edition, Chapter 8, page 472; Official (ISC)2 CISSP CBK Reference, Fifth Edition, Chapter 8, page 572.