some but not all Boolean functions of 3 variables

all function of 3 variables but none of 4 variables

all functions of 3 variables and some but not all of 4 variables

all functions of 4 variablesand some but not all of 4 variables

2 input AND gates only.

2 number of 2-input XOR gates and 6 number of 2-input AND gates.

Two 2-input NOR gates and one XNOR gate.

XOR gates and shift registers.

0

1

$$\overline A B + A\overline B $$

$$\left( {\overline {A \oplus B} } \right) \oplus \left( {\overline {A \oplus B} } \right)$$

F = A $$ \odot $$ C

F = A $$ \oplus $$ C

F = B $$ \odot $$ C

F = B $$ \oplus $$ C