removal of thermostat --pic inside

[Silverbullet]

hey guys, im trying to take out my thermostat to test it because my car dosnt seem to warm up AT ALL driving in this 30-40º weather.

Now... as you may have realized it is real cramped in that area and it is hard to reach ratchets and sockets in there. My question is what exactly do i have to unbolt to acutally take out the thermostat? I can see the 3 bolts holding "B" in the diagram and it is probably the easiest to remove. Can i take out the thermostat from just removing that or would i have to unbolt "A" in the diagram as well? I dont see how i can reach any type of tool in there.

any type of help is appreciated.