To examine the Exhibit， press the Exhibit button. While a user is compiling a C program， "vmstat 120 10" is run to determine the cause of a performance problem.  Given the vmstat output as shown in the exhibit， which of the following conclusions should be drawn about the I/O bottleneck？（）

• A、 There is a file I/O bottleneck.
• B、 There are too many open files.
• C、 There appears to be a buffer shortage.
• D、 There is a paging space I/O bottleneck.