The question is which logic function does this circuit implement if A and B are input and Y is output?

I'm not familiar how 4-terminal MOSFET works but trying to solve Y using A=0 B= 0

The abovest transistor wouldn't be turned on because \$V_{SG} = 0\$

The belowest transistor also cannot be turned on because \$V_{GS}\$ is negative.

For the transistor having \$V_{DD}\$ at base, which side should we choose as a source?