●The construct

cobegin

Statement1；

Statement2；

coend

means Statement1 and Statement2 are to be executed in parallel．The only two atomic actions in this construct are loading the value of a variable and storing into a variable．For the program segment

x=0；y=0；

cobegin

{x=1；y+=x；}

{y=2；x+=3；}

coend

Which of the following indicate(s)possible values for the variables when the segment finishes execution? (74) ．

Ⅰ．x=1，y=2

Ⅱ．x=1，y=3

Ⅲ．x=4，y=6

(74) A．Ⅰ

B．Ⅰ，Ⅱ

C．Ⅰ，Ⅲ

D．Ⅱ and Ⅲ