Ruthenium has atomic number $44$. One oxide of ruthenium is the black solid, X. A sample of X with mass $5.79\,\text{g}$ contains $1.39\,\text{g}$ of oxygen. Determine the empirical formula of X.
- A$\text{Ru}_2\text{O}$
- B$\text{RuO}$
- C$\text{RuO}_2$
- D$\text{RuO}_4$