For what real values of k, other than k \equal{} 0, does the equation x^2 \plus{} kx \plus{} k^2 \equal{} 0 have real roots?
<spanclass=′latex−bold′>(A)</span>k<0<spanclass=′latex−bold′>(B)</span>k>0<spanclass=′latex−bold′>(C)</span>k≥1<spanclass=′latex−bold′>(D)</span>all values of k<spanclass=′latex−bold′>(E)</span>no values of k