If the functions $W, X, Y$ and $Z$ are as follows
\[\begin{array}{l}
W=R+\bar{P} Q+\bar{R} S \\
X=P Q \bar{R} \bar{S}+\bar{P} \bar{Q} \bar{R} \bar{S}+P \bar{Q} \bar{R} \bar{S} \\
Y=R S+\overline{P R+P \bar{Q}+\bar{P} \cdot \bar{Q}} \\
Z=R+S+\overline{P Q+ \bar{P} . \bar{Q} . \bar{R} + P \bar{Q} . \bar{S}}
\end{array}\]
Then
- $W = Z, X = \bar{Z}$
- $W=Z_{1} X=Y$
- $W=Y$
- $W = Y = \bar{Z}$