Which of the following situations are handled by an operating system as part…

Concept: In the standard catalogue of operating-system services, error detection (error handling) is the service through which the OS constantly watches for faults arising in the CPU and memory hardware, in the I/O devices, and in user programs, and then takes corrective action — report the condition, retry the operation, abort the job, or restore a consistent system state.

Guarding the machine against a deliberate external threat such as a virus or a worm is catalogued under a different service, protection and security, which controls access and defends against attackers rather than detecting hardware or device faults. So the test is not “does the OS care about this at all?” but “is this a fault the OS detects and recovers from, or a threat it defends against?”

Applying the test to the three situations

1. Lack of paper in the printer — a fault raised by an I/O device. The printer reports its paper-out status to the driver, and the OS suspends the print job and surfaces the condition to the user. This is the I/O-device branch of error detection.

2. Power failure — a fault in the hardware and power subsystem. Through its power-management facilities the OS reacts: it signals a safe shutdown, flushes buffered data, and restores a consistent state on the next boot. This is the hardware branch of error detection and recovery.

3. Virus protection — not a device or hardware fault at all. A virus is deliberately introduced malicious code, so countering it belongs to the protection-and-security service, and in practice is carried out by antivirus software layered on the operating system.

Cross-check: read each offered combination against that classification. A combination that keeps virus protection inside error handling has to move a security service into the fault-detection service, and a combination that drops the power failure has to remove a hardware fault from a service defined over hardware faults. The only combination consistent with the classification is the printer paper-out condition together with the power failure — that is, (a) and (b).

A common objection: modern operating systems do ship built-in security tools such as Windows Defender or macOS XProtect, so “the OS never touches viruses” would be too strong a claim. The stem here is narrower — it asks what the OS handles as part of error handling — and under that specific heading virus protection is classified under protection and security instead.