Which block cipher mode of operation for encrypting data is simple and efficient and provides...

The correct answer is A — Electronic codebook (ECB).

According to WGU Cybersecurity Architecture and Engineering (KFO1 / D488), ECB mode is the simplest and most basic mode of operation for block ciphers. It encrypts each block of plaintext independently with the same key, but identical plaintext blocks produce identical ciphertext blocks, providing no additional confidentiality beyond the block cipher itself and making patterns visible.

CBC (B), CTR (C), and OFB (D) are more secure and avoid patterns.

Reference Extract from Study Guide:

"Electronic Codebook (ECB) mode encrypts each block independently and is simple but reveals patterns when identical plaintext blocks occur, thus offering minimal confidentiality beyond the underlying cipher."

— WGU Cybersecurity Architecture and Engineering (KFO1 / D488), Block Cipher Modes of Operation

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