The correct answer is: C. 7
DMA stands for Direct Memory Access. It is a feature of some computer systems that allows certain hardware devices to access memory directly, without going through the CPU. This can improve performance, as it can free up the CPU to do other things while the device is transferring data.
The AT class PC has 7 DMA channels. These channels can be used by a variety of devices, including hard drives, floppy drives, and sound cards. The specific device that uses a particular channel is determined by the BIOS.
Option A is incorrect because there are 7 DMA channels, not 3.
Option B is incorrect because there are 7 DMA channels, not 4.
Option D is incorrect because there are 7 DMA channels, not 8.
Option E is incorrect because there are 7 DMA channels, not none.