The types of financial managers are:

• A. a controllers, treasurers, cash and credit managers: These are specific, well-defined roles within a finance department. A controller typically handles accounting and reporting, a treasurer manages cash and investments, a cash manager focuses on liquidity, and a credit manager handles credit policies and collections. These are all distinct types of financial managers based on their functions.
• B. top, middle and lower-level managers: This describes management hierarchy levels, not specific types of financial managers by function. Financial managers can exist at any of these levels.
• C. digital managers: This is a broad term and not a recognized classification for financial managers.
• D. strategic, operational and functional managers: These are general classifications of management based on scope, not specific financial management roles. While financial managers perform strategic, operational, and functional tasks, these terms describe management types in general, not specifically financial managers.

Option A lists specific functional roles that are integral to financial management within an organization.

The final answer is $\boxed{\text{A. a controllers, treasurers, cash and credit managers}}$