4. Consider a standard Ethernet (which implements CSMA/CD and 1-persistent method) with only three stations in a line: the distance between Station A and Station B and between Station B and Station C are both 600 meters. The propagation speed is the speed of light (300,000,000 meters/second). The data rate is 10 Mbps. At time instant t1=0 microsecond, Station A has a frame with size 3,000 bits to be sent. At time instant tz=1 microsecond, Station B has a frame with size 2,000 bits to be sent. At time instant tz=2 microsecond, Station C has a frame with size 1,000 bits to be sent. Please determine the number of bits each station can send during its first transmission attempt. (6 points)