For an octal$-$to$-$binary encoder with three output lines x$,$ y$,$ and z$,$ what is the Boolean function for the output y$?$

a$.$

D$2+$ D$3+$ D$6+$ D$7$

b$.$

D$1+$ D$2+$ D$4+$ D$6$

c$.$

D$1+$ D$3+$ D$5+$ D$7$

d$.$

D$3+$ D$4+$ D$5+$ D$6$