题目内容：
根据下面的文字资料回答题In low-speed network，it is usually adequate to wait for congestion to occur and then react to it by telling the source of packets to slow down．In high-speed networks，this approach oftenworks poorly，because in the（ 1 ）between sending the notification and notification arriving at the source，thousands of additional（ 2 ）may aITive．In ATM network，a major tool for preventing（ 3 ）is（ 4 ）control．when a host wants a new virtual（ 5 ），it must describe the traffic to be offered and the service expected．文中（ 1 ）处正确的答案是（ ）。
A．interval B．time
C．slot
D．delay
参考答案：
答案解析：