At room temperature, the reaction between `NO` and `O_(2)` to give `NO_(2)` is fast, while that between `CO` and `O_(2)` is slow. It is due to:
A. `CO` is smaller in size than that of `NO`
B. `CO` is poisonous
C. The activation energy for the reaction,
`2NO+O_(2) rarr 2NO_(2)` is less than
`2CO+O_(2)rarr 2CO_(2)`
D. None of these