Choice "D" is correct. Proper segregation of duties reduces the opportunities for any individual to both perpetrate and conceal errors or fraud.
Choice "a" is incorrect. Proper segregation of duties typically involves assigning different people the responsibilities of authorizing transactions, recording transactions, and maintaining custody of the related assets. Since journalizing cash receipts and disbursements and preparing the financial statements are both recordkeeping functions, this would not be a violation of proper segregation of duties.
Choice "c" is incorrect. Monitoring internal controls and evaluating whether those controls are operating as intended would properly be performed by one person. Combining these functions does not violate the concept of proper segregation of duties, since it does not encompass an inappropriate combination of authorization, recordkeeping, and custodial functions.
Choice "b" is incorrect. Proper segregation of duties typically involves assigning different people the responsibilities of authorizing transactions, recording transactions, and maintaining custody of the related assets. Since adopting new accounting pronouncements and authorizing the recording of transactions are both authorization functions, this would not be a violation of proper segregation of duties.