The imbalance between uplink and downlink coverage in C-band is not fixed, it varies depending on the network configuration, location, and other factors. Generally speaking, it's hard to provide an exact number for this imbalance, as it depends on the specific network conditions and the equipment used.
However, a common practice is to use more power in downlink than uplink, this is due to the fact that downlink is more sensitive to path loss than uplink, and also because the downlink signal is intended to cover a larger area than the uplink. Therefore, the imbalance is commonly in the range of 3 to 6 dB, and it's more likely to be at the lower end of that range. So, the correct answer is B. 3dB It's worth noting that the C-band is not the most popular frequency band for 5G network deployment, it's just one of the many frequency bands that are being used for 5G deployment, and the most popular frequency bands for 5G deployment vary depending on the country, region, and operator.