The given account codes — CA005, CA006, CA007 — clearly follow a numeric pattern with a common prefix, increasing in sequence. Such codes are known as Sequential codes, where each new entry is given the next number in the sequence. This helps in organization and systematic record-keeping. Other options: - Mnemonic codes use alphabets with meaning (e.g., SUP001 for Super Ltd.) - Block codes use reserved ranges for categories - Encryptic codes are non-intuitive for security reasons