6) Let $K_4 = \{1, (1,2)(3,4), (1,3)(2,4), (1,4)(2,3)\} \subset A_4$. Show that $K_4 \triangleleft A_4$. Write elements of $A_4/K_4$. This $K_4$ is called the Klein 4 group and remember $A_4$ is the alternating group (subgroup of even permutations in $S_4$).