Explanation:

- Optical Character Recognition (OCR):

- Primarily used for converting different types of documents, such as scanned paper documents, PDFs, or images captured by a digital camera, into editable and searchable data.

- Not typically used for attendance marking or security purposes.

- Webcam:

- Used for capturing video and images for various purposes, including video conferencing.

- It can be used in security systems but is not primarily designed for attendance marking.

- Biometric Sensor:

- Specifically designed to recognize individuals based on physical or behavioral traits, such as fingerprints, facial recognition, or iris scans.

- Widely used for marking attendance and for security in organizations and institutions.

- "Both a and c":

- Suggests that both OCR and biometric sensors are used for the same purpose, which is not accurate in general practice.

Correct Answer: Option 3 - Biometric sensor.

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