Two radioactive materials \[{{X}_{1}}\] and \[{{X}_{2}}\] have decay constants \[10\lambda \] and \[\lambda \] respectively. If initially they have the same number of nuclei, then the ratio of the number of nuclei of \[{{X}_{1}}\] to that of \[{{X}_{2}}\] will be 1/e after a time

• A. \[\frac{1}{10\lambda }\]
• B. \[\frac{1}{11\lambda }\]
• C. \[\frac{11}{10\lambda }\]
• D. \[\frac{1}{9\lambda }\]