What is the effect of the following command?

What is the effect of the following command?

$ pr report.txt | lpr
A . The file report.txt is formatted for printing and sent to the l pr program.
B . Tabs are converted to spaces in report.txt, and the result is saved in lpr.
C . The files report.txt and lpr are combined together into one file and sent to standard output.
D . The file report.txt is printed, and any error messages are stored in the file lpr.
E . None of the above.

Answer: A