Which is the correct formula for copper(I) sulfide?

Which is the correct formula for copper(I) sulfide?

A) CuS

B) Cu2S

C) CuS2

D) Cu2S2

E) Cu2S3

Copper(I) sulfide is an ionic compound which means we need to cross multiply the charges (oxidation numbers) to get the correct formula. Cu has a charge of +1 as indicated by the roman numeral in the name and S has a charge of -2 since its in group 16 of the Periodic table. Cross multiplying the numbers (each one gives its number to the partner), we get Cu2S