(c) The respective output of each logic gate is shown below
Here, Y′=A⋅B=A+BY′′=A⋅(A+B)=A+(A+B)[By de Morgan's theorem]=A+(A⋅B)=A+(A⋅B)Y′′′=B⋅(A+B)=B+A+B=B+(A⋅B)=B+(A⋅B)Y=Y′′⋅Y′′′=A+(A⋅B)⋅[B+(A⋅B)]=[A+A⋅B]+[B+(A⋅B)]=A⋅(A⋅B)+B⋅(A⋅B)=A(AB)+B(AB)=(A+B)(A⋅B)=(A+B)(A+B)=AA+AB+BA+BB=0+AB+BA+0=A⋅B+A⋅B