下列各句中，加点的词语使用正确的一句是（   ）

A．中国足球为什么一直在低水平徘徊，不能走向世界？个中委屈绝非三言两语能说清楚。

B．目前，为了从根本上扭转我国经济在世界经济危机中的下滑趋势，中央采取了着力扩大内需，特别是促进居民消费需求的政策措施，这是十分正确的。

C．中国当代艺术有某种哗众取宠的特征，大量的作品，虽然在短期内或许会成为市场的热点，形成一段时间的行情，但是从本质上是一文不名的。

D．由于楼盘前临碧水背依青山，环境十分优美，发售第一天便十室九空，销售场面十分火爆。

A transport layer protocol has several responsibilities. One is to create a process-to-process (program-to-program) communication, TCP uses port (1) to accomplish this. Another responsibility of a transport layer protocolis to create a  (2) and error-control mechanism at the transport level. TCP uses a sliding(3) protocol to achieve flow control. It uses the acknowledgment packet, time-out, and retransmission to achieve(4) control. The transport layer is also responsible for providing a connection mechanism for the application program. The application program sends  (5) of data to the transport layer. It is the responsibility of the transport layer at the sending station to make a connection with the receiver.

空白（1）处应选择（）

A.numbers

B.connections

C.diagrams

D.resources