I have Acrobat Pro X (10.1.13). In the print monitor, there is no box that allows me to select single-sided printing. Under "Size Options" there is only "Fit," "Actual Size," and "Shrink oversized pages."

Not quite right, but I figured it out anyway.  In the print dialog, when printing a pdf doc from Acrobat Pro on my Mac, there is a button on the lower left that says "PRINTER." When I click that, I get a message saying that I should ideally set all print options from the Application print dialog box, but can't do that for this option, so I click the "yes" button (to "do you want to continue").  That displays yet another dialog box (called "Printer") which has a box to check for "Two-sided."  One then has to click the "Print" button to save the setting (not to print, but to save, go figure!), and it takes you back to the original Application printer dialog box.  There, you have to click the "Print" button to make the printer print.  I presume Adobe has improved this process in newer versions because this is truly convoluted.