[单选题]
High-energy photons f v.u(nsgv oa7h: *ed4areghhodjs tgx:g:eqa00)cz ks2 260g y* used to bombard an unknown metal. The strongest peak is found for X-rays with an energy of 6hgqc6ytxsa g:2o 0e:g20 s)j0dzhk *g6 keV. What is the atomic number of the metal?
