Consider a system represented by the block diagram shown below. Which of the following signal flow graphs represent(s) this system? Choose the correct option(s).

A 3-input majority logic gate has inputs $X, Y$ and $Z$. The output $F$ of the gate is logic ' 1 ' if two or more of the inputs are logic ' 1 '. The output $F$ is logic ' 0 ' if two or more of the inputs are logic '0'. Which one of the following options is a Boolean expression of the output $F$ ?

A full adder and an XOR gate are used to design a digital circuit with inputs $X, Y$, and $Z$, and output $F$, as shown below. The input $Z$ is connected to the carry-in input of the full adder.

If the input $Z$ is set to logic ' 1 ', then the circuit functions as __________ with $X$ and $Y$ as inputs.

A 4-bit weighted-resistor DAC with inputs $b_3, b_2, b_1$, and $b_0$ (MSB to LSB) is designed using an ideal opamp, as shown below. The switches are closed when the corresponding input bits are logic ' 1 ' and open otherwise. When the input $b_3 b_2 b_1 b_0$ changes from 1110 to 1101, the magnitude of the change in the output voltage $V_O$ (in mV , rounded off to the nearest integer) is ____________.