Oxygen possesses three stable isotopes, $^{16}\text{O}$, $^{17}\text{O}$ and $^{18}\text{O}$. A specimen of oxygen gas, $\text{O}_2$, contains all three isotopes and is examined with a mass spectrometer. How many peaks caused by the $\text{O}_2^+$ ion would be expected?
- A3
- B5
- C6
- D9