Hi again,
In your diagram, A is the controlling signal controlling the tri state state. B is simply an inverter so the input B to output is:
0,1
1,0
Note that when A is low N2 and P2 are in the OFF state so B can not cause any output. It's only when A goes high that N2 and P2 turn on and so then B is allowed to set the output, and since B is connected to an inverter, the output is C=B' which is an inverter. Since A controls the tri state state, we have for inputs A and B and output C:
A-B-C
0-1-z
0-0-z
1-1-0
1-0-1
or
C=B' when A is high, and
C=z when A is low.
That's a tri state inverter.