Transition Metal Ions Typically Lose Their Outermost Ns Electrons Before

Transition metal ions typically lose their outermost ns electrons before losing any (n - 1) d electrons.What is the best explanation of this frequently observed trend?

A) The ns electrons have lower angular momentum.
B) The (n - 1) d electrons have a larger average radius.
C) The (n - 1) d orbitals can have more electrons with unpaired spins.
D) The (n - 1) s and (n - 1) p subshells are full.
E) The (n - 1) d electrons experience a higher Z_eff than the ns electrons.