Clutch Cylinder or Slave Cylinder?

I had posted a few topics since my clutch pedal went to the floor and never came back. Checked the pins and theyre fine as well as the rod. i was told to replace the clutch cylinder so i called Car Quest and there are 2 different ones and a slave cylinder. Which could be my culprit? One is $117 and the other is 106. No idea which could be the one...

The master cylinder is on the engine side of the firewall below the brake booster. Best way to check is to look inside where the clutch pedal rod enters the firewall and see if any fluid is leaking - when it starts to fail you should see a trail of fluid running down behind the carpet. The slave cylinder is a lot more complex, because on these SC's it's integral with the clutch release system and unfortunately the trans has to be removed to replace it. So I'd try to bleed the system first then establish which cylinder is failing. Last year when the weather started to get colder my '93 did the same thing, (pedal suddenly went to the floor) the seal in the slave cylinder stiffened-up and it dumped all the fluid. I refilled it and it was ok for quite a while. However, with 200,000m on the original clutch I pulled the trans and replaced everything including the master cylinder. I believe I paid about $40 for the slave and around a $100 for the master.

So you think i got some air in the system? I didnt think it was the slave cylinder becuase when they go its dead completely. Hopefully I can bleed it down and it will work until I can get it replaced.