The minimum size of smoke particle is

• A. 0.2‚âà√≠¬¨‚à´m
• B. 1‚âà√≠¬¨‚à´m
• C. 0.8‚âà√≠¬¨‚à´m
• D. 0.5‚âà√≠¬¨‚à´m