Dida, try this: place one drop of Maco solution B on a little strip of Fomabrom. With the lights on. See if there is a color change within the minute. Color change indicates there are developers incorporated, and the paper won't lith. Try it on a little swatch of the other two papers to compare. I pick up a lot of old papers from here and there, and it's a quick test to see what has potential and what doesn't.