As shown in the figure, there are four users under the same antenna of an AP. They all need to transmit data. It is known that User1 has occupied the channel for 3 times and transmits a round of…

As shown in the figure, there are four users under the same antenna of an AP. They all need to transmit data. It is known that User1 has occupied the channel for 3 times and transmits a round of data for 2 times; User2 has occupied the channel for 4 times and transmits a round of data for 4 times; User3 has occupied the channel for 6 times and transmits a round of data for 6 times; User4 has occupied the channel for 7 times and transmits a round of data for 7 times. After the Airtime scheduling function is enabled, according to the Airtime scheduling mechanism, which of the following users will be prioritized for scheduling ?