Sue ... Optimized and progressive are both option for saving images for the web, which you should not use when saving for printing as you want to have maxximum quality.  When preparing your image for posting to the web, selecting porgressive will make an image appear in the browser first in a low res, while downloading the higer resoulution in the background.  

Just as a sidebar to this reply, if you saved your image as optimized, and reopen it, the next time you open and try to resave it will by default to to optimized again.

For printing select standard at the highest quality.  If you are printing a poster size print, quite often large size printers use RIP software to print the image.  When selecting the resolution for your image always consult with your processing lab to see what resolution they want when printing posters.  At Stan C. Reade's lab for poster printing you can save your image at 150 dpi.