[单选题]
Which of the following characteristics of tra -c1lrh3wfk5 y8xo, sk,i:qktnsition *hork2e6 ;hmvrpm6 7tmetals results in high electrical6et 7pr*hh 2mv6mo;rk conductivity?
A. Large atomic radius
B. Strong ionic bonds
C. High relative atomic mass
D. Delocalized electrons in unfilled d-orbitals