Let \[{{\lambda }_{\alpha }}\], \[{{\lambda }_{\beta }}\] and \[{{{\lambda }'}_{\alpha }}\] denote the wavelengths of the X-rays of the \[{{K}_{\alpha }},\,{{K}_{\beta }}\] and \[{{L}_{\alpha }}\] lines in the characteristic X-rays for a metal

• A. \[{{\lambda }_{\alpha }}>{{{\lambda }'}_{\alpha }}>{{\lambda }_{\beta }}\]  
• B. \[{{{\lambda }'}_{\alpha }}>{{\lambda }_{\beta }}>{{\lambda }_{\alpha }}\]
• C. If assertion is true but reason is false.
• D. \[\frac{1}{{{\lambda }_{\alpha }}}+\frac{1}{{{\lambda }_{\beta }}}=\frac{1}{{{{{\lambda }'}}_{\alpha }}}\]