181. Traces of inert gas constituents may be present even after aerating. What are the limits for carbon dioxide (CO2) and carbon monoxide?

A. CO, <1.5% BV and CO <150ppm
B. CO, <1.5% BV and CO <250ppm
C. CO_g <1.0%BV and CO <50ppm
D. CO, <0.5% BV and CO <50ppm