D. It is used to add sound effects.
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Answer:
3. System Software
Explanation:
An operating system is a special type of system software. It controls and co-ordinates overall of the computer.
Answer:
Physical / Data link layer
Explanation:
If two computers (A & B) are directly connected through Ethernet cable. A is sending data to B, the data would be transmitted if the network is clear but if the network is not clear, the transmission would wait until the network is clear.
The Open Systems Interconnection model (OSI model) has seven layers each with its own function.
The physical layer is the first layer responsible for data transmission over a physical link. The data packets are converted to signals over a transmission media like ethernet cable.
The data link layer is the second layer in the OSI layer responsible for transmission of data packets between nodes in a network. It also provides a way of detecting errors and correcting this errors produced as a result of data transmission.