单项选择题

A. A single serial network between Node ’A’ and Node ’B’ and Node ’C’
B. A point-to-point link between Node ’A’ and Node ’C’,and Node ’B’ and Node ’C’
C. A serial network between Node ’A’ and Node ’C’,and a serial network between Node ’B’ and Node ’C’
D. A point-to-point link between Node ’A’ and Node ’B’ Node ’B’ and Node ’C’ and Node ’A’ ad Node ’C’