The correct answer is: C. Sometimes require header.
In synchronous transmission, data is transmitted in blocks. Each block is preceded by a header that contains information about the block, such as its length and the address of the destination. This information is necessary for the receiver to correctly decode the data.
However, there are some cases where synchronous transmission does not require a header. For example, if the data is being transmitted over a dedicated line, the receiver can be pre-configured with the address of the sender. In this case, the header is not necessary and can be omitted.
Overall, whether or not a header is required for synchronous transmission depends on the specific circumstances. In most cases, a header is necessary to ensure that the data is correctly decoded. However, there are some cases where a header can be omitted.
Here is a brief explanation of each option:
- Option A: Require header. This is the most common case. In synchronous transmission, data is transmitted in blocks. Each block is preceded by a header that contains information about the block, such as its length and the address of the destination. This information is necessary for the receiver to correctly decode the data.
- Option B: Do not require header. This is less common, but it can happen in some cases. For example, if the data is being transmitted over a dedicated line, the receiver can be pre-configured with the address of the sender. In this case, the header is not necessary and can be omitted.
- Option C: Sometimes require header. This is the most accurate option. In most cases, a header is necessary to ensure that the data is correctly decoded. However, there are some cases where a header can be omitted.
- Option D: All of the above. This is not accurate. While it is true that synchronous transmission can require a header, it is not always necessary.
- Option E: None of the above. This is also not accurate. While it is true that synchronous transmission can sometimes omit a header, it is not always the case.