The number of people invited __________ fifty, but a number of them __________ absent for different reasons

A．were ; was

B．was ; was

C．was ; were

D．were ; were

下列关于我国证券交易所的表述中，正确的有 ( )

A．证券交易所是非盈利的经济组织

B．证券交易所参与证券的交易

C．为证券交易提供设施和服务

D．组织监督证券交易、结算和交割

E．对违法违规行为进行处罚