`1` of `NO_(2)` and `7//8 L` of `O_(2)` at the same temperature and pressure were mixed together. What is the relation between the mases of the two gases in the mixture?
A. `M_(N_(3))=3M_(O_(2))`
B. `M_(N_(2))=8M_(O_(2))`
C. `M_(N_(2))=M_(O_(2))`
D. `M_(N_(2))=16M_(O_(2))`