The correct answer is Motherboard.

• The software and hardware of a computer get instructions for processing a task that is generated or produced by a complex and heavy set of electronics devices that are embedded on a platform which is known as a motherboard.
• The motherboard allows communication to and between the CPU, RAM, and all other computer hardware components.
• A motherboard (also called mainboard, main circuit board, system board, baseboard, planar board, logic board, or mobo) is the main printed circuit board (PCB) in general-purpose computers and other expandable systems.
• It holds and allows communication between many crucial electronic components of a system, such as the central processing unit (CPU) and memory, and provides connectors for other peripherals.  

• HDD:-
  • A hard disk drive (sometimes abbreviated as a hard drive, HD, or >HDD) is a non-volatile storage device.
  • It is usually installed internally in a computer, attached directly to the disk controller of the computer's motherboard.
• SMPS:-
  • SMPS or switched-mode power supply is an electronic device that is used to convert AC to DC, AC to AC, DC to DC, and DC to AC voltages. 
• RAM:-
  • It is called 'volatile' memory by analogy because if the computer loses power, all the data stored in RAM (or other volatile memory) is lost or 'evaporates'.