题目内容：
根据下列题干，回答题：Flow control is a function that prevents network congestion by ensuring that （ 1 ）do not over- whelm （ 2 ）with data. There are three commonly used methods for handhng network congestion. （ 3 ）is used by network devices to temporarily store bursts of excess data in memory until they can be processed.（ 4 ） are used by receiving devices to help prevent their buffers from overflowing. （ 5 ）is a flow -control scheme in which the source device requires an acknowledgment from the destination after a certain num- ber of packets have been transmitted.
请选择（ 1 ）处最佳答案
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