What is the correct relationship between the $pH$s of isomolar solutions of sodium oxide ($pH_1$), sodium sulphide ($pH_2$), sodium selenide ($pH_3$) and sodium telluride ($pH_4$)?

Question

(a) $pH_1 > pH_2 = pH_3 > pH_4$

(b) $pH_1 < pH_2 < pH_3 < pH_4$

(c) $pH_1 < pH_2 < pH_3 \approx pH_4$

(d) $pH_1 > pH_2 > pH_3 > pH_4$