When the Following Equations Are Balanced Using the Smallest Possible $\rightarrow$

When the following equations are balanced using the smallest possible integers, what is the number in front of the underlined substance in each case?
-Sb(s) + O₂(g) $\rightarrow$ Sb₂O₅(s)

A) 1
B) 2
C) 4
D) 6
E) 12