a virus that spreads in a computer is a type of malicious computer program. Computer viruses are software programs designed to replicate themselves and spread from one computer to another. They can attach themselves to legitimate programs or documents, and when the infected program or document is executed, the virus activates and starts spreading to other files and systems. Viruses can cause various harmful effects, such as corrupting or deleting files, stealing sensitive information, or disrupting computer operations. Antivirus software and best practices, such as avoiding suspicious downloads and email attachments, are used to protect computers from these malicious programs.

1. Optical Mark Reading (OMR) is a method of entering data into a computer system.

2. Optical mark readers read pencil or pen marks made in pre-determined positions on paper forms as answers to questions or tick list signs.

All three components—COAX (coaxial cables), Fiber (optical fiber cables), and STP (shielded twisted pair cables)—can be used in LANs for Ethernet connectivity, depending on specific network requirements and conditions. Different types of Ethernet cables, including coaxial, fiber optic, and shielded twisted pair, are used based on factors such as data transfer speed, distance, and susceptibility to electromagnetic interference.

A switching hub, also known as a network switch, is designed to send packets using package addresses. A network switch operates at the data link layer of the OSI model and uses MAC addresses to forward data frames to specific devices within a local area network (LAN). Unlike a hub, which simply broadcasts data to all devices in the network, a switch intelligently forwards packets only to the device intended to receive the data, increasing network efficiency and reducing unnecessary network traffic.