Statement A- Satellite communication uses different frequency bands for uplink and downlink.
Statement 2- Bandwidth of video signal is 4.2MHz.
A. A is true but B is false
B. A is false but B is true
C. A and B are false
D. A and B are true

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Hint:For satellite communication (also written as satcom) satellites have to use a wide range of frequencies for uplink and downlink and this depends on the different requirements of signal transmissions.

Complete answer:
In satellite communications we have to use different pairs of bands, of uplink and downlink.
Few of the various frequency bands are given below:
1. UHF band – The frequency range of this band is from 0.25 GHz to 0.27 GHz. UHF band is used in military applications.
2. S band – The frequency of S band ranges from 1.8 GHz to 2.3 GHz. This band is used for TV transmission.
3. C band – The frequency range is 3.7 GHz to 4.2 GHz and this band is used for TV broadcast.
4. X band – Frequency range is from 7.25 GHz to 7.75 GHz and it is used by the military.

These different frequency bands are used to avoid interference. Therefore, the statement A is true.The bandwidth of the video signal is 4.2 MHz. This means that the statement 2 is also correct.

Hence, the correct option is D.

Note: In satellite telecommunication, a downlink is the link from a satellite down to a station or receiver, while an uplink is the link from a ground station up to a satellite. Since, we can have different stations and satellites, there are different frequency bands for uplink and downlink. Also, since video signals have quite large data, they have to be transmitted in high bandwidths like 4.2 MHz.