单选题Which function enforces logical data throughput rates that are below the actual physical line rate of a port?（）A rate limitingB data policingC classificationD bandwidth limiting

The objective of (71) is to determine what parts of the application software will be assigned to what hardware. The major software components of the system being developed have to be identified and then allocated to the various hardware components on which the system will operate. All software systems can be divided into four basic functions. The first is (72). Most information systems require data to be stored and retrieved, whether a small file, such as a memo produced by a word processor, or a large database, such as one that stores an organization's accounting records. The second function is the (请作答此空), the processing required to access data, which often means database queries in Structured Query Language. The third function is the (74), which is the logic documented in the DFDs, use cases, and functional requirements. The fourth function is the presentation logic, the display of information to the user and the acceptance of the user's commands. The three primary hardware components of a system are (75).

A. data persistence
B .data access objects
C. database connection
D. data access logic