Analyzing the coding scheme:
\begin{itemize}
\item[(A)] Block codes: Assign ranges or 'blocks' of numbers/codes to specific categories. Here, codes CA005, CA006, CA007 seem to be assigned to specific accounts (likely Customers or Suppliers, represented by 'CA'). While not a strict range, the pattern 'CA' followed by sequential numbers suggests a block allocated for this type of account.
\item[(B)] Mnemonic codes: Use letters or abbreviations that aid memory (e.g., 'ACC' for Accounts, 'PUR' for Purchase). 'CA005' doesn't inherently suggest 'Super Ltd'.
\item[(C)] Encryptic codes: Codes designed to conceal information. Not evident here.
\item[(D)] Sequential codes: Assign numbers in simple consecutive order (1, 2, 3...). While 005, 006, 007 are sequential, the prefix 'CA' makes it more specific than just sequential.
\end{itemize}
The structure 'CA' (likely signifying 'Customer Account' or similar) followed by a numerical sequence fits the description of block codes, where a specific block starting with 'CA' is used for these accounts.