For signed number, foumbit binary adder$-$subtractor can detect overflow. Which of the followings is true related to this detection?

A$.$ An of them.

B$.$ When there is an overflow $M=1.$

C$.$ It can not detect overflow for negative numbers.

D$.$ When there is an overflow $V=1.$

E$.$ When there is overflow, the signals entering the exclusive$-$OR gate, prior to V output, are equal to each other.

If one wants use $4-$bit binary $(4$BB$)$ adder as an BCD adder some problems occur. To solve these problems the table, which is available, should be studied and a Boolean expression should be obtained for the numbers that $6(0110)$ should be added. Which one of the followings is that Boolean expression.

A$.BCD=Z_8{Z}_4+Z_2+0110$

B$.BCD=4BB+0110$

C$.C=K+Z_8{Z}_4+Z_8{Z}_2$

D$.BCD=Z_8{Z}_4{Z}_2+0110$

E$.$ None of these.

Which one of the followings is correct related to BCD adder whose block diagram is available?

A$.$ All of them.

B$.$ When there is carry in the initial $4-$bit binary adder, $0110$ is added to the sum in the second $4-$bit binary adder.

C$.$ When $Z_4$ and $Z_2$ is equal to $1$ in the initial $4-$bit binary adder, $0110$ is not added to the sum in the second $4-$bit binary adder.

D$.$ When $Z_8$ and $Z_4$ is equal to $1$ in the initial $4-$bit binary adder, $0110$ is added to the sum in the second $4-$bit binary adder.

E$.$ When $Z_8$ and $Z_2$ is equal to $1$ in the initial $4-$bit binary adder, $0110$ is added to the sum in the second $4-$bit binary adder.