Sodium ions, $\text{Na}^+$, together with oxygen ions, $\text{O}^{2-}$, join with chromium ions to produce a salt. For sodium dichromate, the formula is $\text{Na}_2\text{Cr}_2\text{O}_7$. What is the oxidation state of chromium in this salt?
- A+2
- B+3
- C+6
- D+12