The threshold for indirect absorption occurs at wavelength __________

• A. 3.01 ‚âà√≠¬¨‚à´m
• B. 2.09 ‚âà√≠¬¨‚à´m
• C. 0.92 ‚âà√≠¬¨‚à´m
• D. 1.09 ‚âà√≠¬¨‚à´m