A level chem; Transition metals

Hi, I am a little lost on the answer to this question, which is D.
What is the electronic configuration of the stable scandium ion?
A [Ar] 3d0 4s2
B [Ar] 3d1 4s1
C [Ar] 3d0 4s1
D [Ar] 3d0 4s0

I learnt that the most stable ion, is when the element d orbital is partially filled, making it a transition metal.
Am I wrong?

Thanks