Final answer:
Register memory is the type of memory directly available to the CPU and is often part of it, used for quickly accessing data necessary for performing currently executed instructions.
Step-by-step explanation:
The type of memory that is directly available to the CPU and is often part of the CPU is A. Register memory. Registers are small, fast storage locations within the CPU designed to hold immediate data for ongoing operations. They are essential for the CPU's functioning as they provide the quickest access to data needed for execution of instructions. Unlike Virtual memory, which is an extension of physical memory managed by the operating system, or RAM (Random Access Memory), which is the main memory used to store data temporarily as the CPU processes it, or ROM (Read-Only Memory), which stores firmware that is not meant to be regularly changed, register memory is integrated within the CPU for speed.