The operating system (OS) is the primary software that manages all the hardware and other software on a computer. It acts as an intermediary between users and the computer hardware. The OS handles basic tasks such as controlling and allocating memory, prioritizing system requests, controlling input and output devices, facilitating networking, and managing files. Examples include Windows, macOS, and Linux.

Electronic Codebook (ECB)is thesimplest modeof block cipher operation, but it encrypts each blockindependently, which results inidentical ciphertext for identical plaintext blocks- making itunsafe for use with structured or repetitive data.
NIST SP 800-38A (Recommendation for Block Cipher Modes of Operation):
"ECB reveals patterns in plaintext and should not be used when such patterns are meaningful and predictable." Though efficient, ECB lackssemantic securityand is rarely recommended in practice.
#WGU Course Alignment:
Domain:Cryptography
Topic:Evaluate block cipher modes for appropriate use cases

Mandatory Access Control (MAC)is the access control model used in environments that manage classified information such as government or military systems. Under MAC, access is based onsecurity labels(e.g., Top Secret, Confidential), and userscannot changeaccess controls.
NIST SP 800-53 Rev. 5 - AC-3 (Access Enforcement):
"MAC policies enforce access based on system-enforced labels, without user discretion, and are ideal for high- security environments where strict data control is essential." MAC is theonly modelwhere access control decisions arecentrally controlled and enforced by a policy administrator, making it ideal for environments requiringdata labeling and user classification.
#WGU Course Alignment:
Domain:Access Control and Identity Management
Topic:Understand and apply MAC for high-security environments

The correct answer is A - Calculating and comparing the hash values of the software code before and after transfer using FTP can help detect any changes and ensure the integrity of the code.
According to WGU Cybersecurity Architecture and Engineering (KFO1 / D488), verifying the integrity of transferred files can be done by using cryptographic hash functions. Comparing pre- and post-transfer hashes ensures that the data was not tampered with during transmission.
Intrusion detection (B) focuses on unauthorized access. Access control (C) protects the server but does not ensure file integrity. Backups (D) provide data recovery but do not validate file integrity during transfers.
Reference Extract from Study Guide:
"Hashing verifies data integrity by allowing a comparison of original and received file values, ensuring no tampering occurred during transit."
- WGU Cybersecurity Architecture and Engineering (KFO1 / D488), Data Integrity Assurance

The correct answer is B - Elliptic Curve Diffie-Hellman (ECDH).
WGU Cybersecurity Architecture and Engineering (KFO1 / D488) material highlights that ECDH is an enhanced, more efficient form of the traditional Diffie-Hellman key exchange, using elliptic curve cryptography (ECC). It provides similar security with much smaller key sizes, improving performance and efficiency.
DH (A) is the traditional method but is less efficient. RSA (C) is primarily used for encryption and digital signatures. DSA (D) is used for digital signatures, not for key exchange.
Reference Extract from Study Guide:
"Elliptic Curve Diffie-Hellman (ECDH) enhances traditional key exchange by utilizing elliptic curve cryptography, offering higher security with smaller key sizes and improved efficiency."
- WGU Cybersecurity Architecture and Engineering (KFO1 / D488), Cryptographic Key Management