The best way to protect sensitive information such as personally identifiable information (PII) stored in a particular data format while allowing the software developers to use it in development and test environments is data masking. Data masking is a technique that replaces or obscures sensitive data elements with fictitious or modified data elements that retain the original format and characteristics of the data. Data masking can help protect sensitive information such as PII stored in a particular data format while allowing the software developers to use it in development and test environments by preventing the exposure or disclosure of the real data values without affecting the functionality or performance of the software or application. The other options are not as effective as data masking in protecting sensitive information such as PII stored in a particular data format while allowing the software developers to use it in development and test environments, as they have different limitations or drawbacks. Data tokenization is a technique that replaces sensitive data elements with non-sensitive tokens that have no intrinsic value or meaning. Data tokenization can protect sensitive information such as PII from unauthorized access or theft, but it may not retain the original format and characteristics of the data, which may affect the functionality or performance of the software or application. Data encryption is a technique that transforms sensitive data elements into unreadable or unintelligible ciphertext using an algorithm and a key. Data encryption can protect sensitive information such as PII from unauthorized access or modification, but it requires decryption to restore the original data values, which may introduce additional complexity or overhead to the software development process. Data abstraction is a technique that hides the details or complexity of data structures or operations from users or programmers by providing a simplified representation or interface. Data abstraction can help improve the usability or maintainability of software or applications, but it does not protect sensitive information such as PII from exposure or disclosure. References: CISA Review Manual (Digital Version), Chapter 5, Section 5.3.2