The correct answer is C. Controller board.
An EIDE drive is a type of hard drive that uses the Enhanced Integrated Drive Electronics (EIDE) interface. EIDE is a standard interface that allows hard drives to communicate with the computer’s motherboard. To install an EIDE drive, you will need to have a motherboard that supports EIDE. If your motherboard does not support EIDE, you will need to upgrade your motherboard or purchase a controller card that provides EIDE support.
RAM (Random Access Memory) is a type of memory that is used to store data that the computer is currently using. BIOS (Basic Input/Output System) is a small program that is stored on a chip on the motherboard. The BIOS is responsible for initializing the hardware and loading the operating system when the computer is turned on. A 286 CPU is a type of central processing unit (CPU) that was released in 1982. An ISA motherboard is a type of motherboard that uses the Industry Standard Architecture (ISA) bus. The ISA bus is a standard bus that was used for connecting expansion cards to computers from the early 1980s to the mid-1990s.
None of the other options are necessary to install an EIDE drive.