In relation to the management and administration of companies limited by shares:

(a) State and explain what is meant by a major transaction. (4 marks)

患者，男，60岁，突然感到心前区闷痛，伴心悸3小时，自服硝酸甘油1片，疼痛未能缓解。做心电图检查，显示如图所示。

该患者意识丧失的最可能原因是（）。

A.心肌病

B.主动脉夹层

C.急性肺栓塞

D.主动脉瓣狭窄

E.急性心肌梗死