A TCP/IP application receives files from a remote machine.  The application reads 32 kilobytes of data at a time to the socket， but has not issued a system call to set the window size. Which of the following procedures should be performed on the personal machine to increase the throughput of the application？（）

• A、 Increase the size of thewall
• B、 Increase the size of sb_max
• C、 Increase the size of tcp_recvspace
• D、 Increase the size of tcp_sendspace