Two water closets are roughed in at a distance of $254$ millimetres $(10$

inches$)$ from the completed walls. What is the c$-$c spacing of the sleeves if the

partition is $125$ mm $(5$ in$)$ hollow tile and the wall finish is $19$ mm $(3/4$ in$)$ plaster?

a$)652$ mm $/253/4$in$.$

b$)698$ mm $/271/2$in$.$

c$)335$ mm $/131/4$in$.$

d$)671$ mm $/261/2$in