Code repositories are a common source of unintentional corporate credential leakage, especially in cloud environments. Developers may accidentally commit and push sensitive information, such as API keys, passwords, and other credentials, to public or poorly secured repositories. These credentials can then be accessed by unauthorized users, leading to security breaches. Ensuring that repositories are properly secured and that sensitive data is never committed is critical for protecting against this type of leakage.
References =
* CompTIA Security+ SY0-701 Course Content: Domain 03 Security Architecture.
* CompTIA Security+ SY0-601 Study Guide: Chapter on Threats and Vulnerability Management.

Detailed Explanation:MAC filtering allows network administrators to control device access by specifying allowed MAC addresses. This prevents unauthorized devices, such as a laptop plugged into a network port, from gaining access. Reference: CompTIA Security+ SY0-701 Study Guide, Domain 2: Threats and Vulnerabilities, Section: "Network Access Control Methods".

An air-gapped network is a network that is physically isolated from other networks, such as the internet, to prevent unauthorized access and data leakage. However, an air-gapped network can still be compromised by removable devices, such as USB drives, CDs, DVDs, or external hard drives, that are used to transfer data between the air-gapped network and other networks. Removable devices can carry malware, spyware, or other malicious code that can infect the air-gapped network or exfiltrate data from it. Therefore, removable devices are the most common data loss path for an air-gapped network. References: CompTIA Security+ Study Guide: Exam SY0-701, 9th Edition, Chapter 9: Network Security, page 449 1

Data masking replaces sensitive data with realistic but fictional data, preserving format and usability while protecting confidential information during testing in environments like UAT (User Acceptance Testing).
Tokenization (B) replaces data with tokens but is more common for payment data in production. Obfuscation (C) scrambles data but is less structured than masking. Encryption (D) protects data confidentiality but may not be practical for testing.
Data masking is a best practice for protecting sensitive data in non-production environments covered in the General Security Concepts domain#6:Chapter 7 CompTIA Security+ Study Guide#.