Answer:

Microcontrollers are integrated circuits that are designed to perform specific tasks and are commonly used in embedded systems. They consist of various components that allow them to execute tasks efficiently and effectively. A microcontroller should at least consist of the following components:

1. CPU:
The CPU (Central Processing Unit) is the brain of the microcontroller. It performs all the arithmetic and logical operations, executes instructions, and controls the overall functioning of the microcontroller.

2. RAM:
RAM (Random Access Memory) is the temporary memory that is used by the microcontroller to store data and instructions during program execution. It is volatile memory, meaning its contents are lost when power is turned off.

3. ROM:
ROM (Read-Only Memory) is non-volatile memory that contains the program instructions and data that are permanently stored. These instructions are read-only and cannot be modified during program execution.

4. I/O Devices:
I/O (Input/Output) devices allow the microcontroller to interact with the external world. These devices include sensors for input, such as temperature sensors, light sensors, etc., and actuators for output, such as LEDs, motors, etc.

5. Serial and Parallel Ports:
Serial and parallel ports are used for data communication between the microcontroller and other peripherals or devices. Serial ports transmit data one bit at a time, while parallel ports transmit multiple bits simultaneously.

6. Timers:
Timers are used to keep track of time and generate accurate timing intervals. They are essential for applications that require precise timing, such as controlling motor speed, generating PWM signals, etc.

Having all these components in a microcontroller ensures that it can perform a wide range of tasks efficiently and effectively. The CPU executes instructions stored in ROM and uses RAM for temporary storage. I/O devices allow the microcontroller to interact with the external world, while serial and parallel ports enable data communication. Timers provide accurate timing intervals for various applications.

Therefore, the correct answer is option 'C' - a microcontroller should consist of CPU, RAM, ROM, I/O devices, serial and parallel ports, and timers.