Introduction:
Interrupts are signals that are generated by external devices or internal processes to gain the attention of the processor. When an interrupt occurs, the processor suspends its current execution and transfers control to a specific interrupt handler routine. Interrupts can be classified into various types based on their source, such as internal interrupts, external interrupts, software interrupts, and hardware interrupts.

Explanation:
Among the given options, the correct answer is option 'B' - external interrupts. Here's why:

External Interrupts:
- External interrupts are generated by external devices connected to the computer system, such as keyboards, mice, timers, and peripheral devices.
- These interrupts are asynchronous and occur independently of the current program execution.
- External interrupts are typically used to handle time-sensitive events or to handle input/output operations from devices.
- They have a higher priority compared to other interrupts as they require immediate attention from the processor.
- Examples of external interrupts include keyboard interrupts, mouse interrupts, and interrupt requests (IRQs) from peripheral devices.

Other Interrupts:
Let's briefly explain the other types of interrupts mentioned in the options:

- Internal Interrupts (Option 'A'):
- Internal interrupts are generated by internal processes or operations within the processor itself.
- They are synchronous and occur during the execution of the current program.
- Examples of internal interrupts include divide-by-zero exceptions, illegal instruction exceptions, and overflow exceptions.
- While internal interrupts are important for error handling and exceptional situations, they do not directly generate fast interrupt exceptions as mentioned in the question.

- Software Interrupts (Option 'C'):
- Software interrupts, also known as system calls, are generated by the execution of specific software instructions.
- They are used to request services from the operating system or to perform privileged operations.
- Examples of software interrupts include system calls for file operations, process management, and memory allocation.
- Software interrupts are not directly related to fast interrupt exceptions.

- Hardware Interrupts (Option 'D'):
- Hardware interrupts are generated by specific hardware signals or conditions, such as I/O device requests or completion of data transfers.
- They can be generated by various hardware components, including timers, I/O controllers, and interrupt controllers.
- Hardware interrupts can have different priorities and can be used for efficient handling of hardware-related events.
- While hardware interrupts are essential for handling external events, they do not specifically generate fast interrupt exceptions as mentioned in the question.

Conclusion:
In conclusion, among the given options, external interrupts are the ones that generate fast interrupt exceptions. External interrupts are generated by external devices connected to the computer system and require immediate attention from the processor. Other types of interrupts, such as internal interrupts, software interrupts, and hardware interrupts, are important for different purposes but do not directly generate fast interrupt exceptions.