[单选题]
Which of the following chcy4 ji,l q 60riyg ;we( rtmk-y,r07gaaracteristics of transitlxbu0145 bmuaion metals results in high electrical condu1 uux0bm 4bla5ctivity?
A. Large atomic radius
B. Strong ionic bonds
C. High relative atomic mass
D. Delocalized electrons in unfilled d-orbitals