Which of the following pair is not isoelectronic species?
(Atomic numbers Sm=62; Er=68; Yb=70; Lu=71; Eu=63; Tb=65; Tm=69)

A

$$Sm^{2+}$$ and $$Er^{3+}$$

B

$$Yb^{2+}$$ and $$Lu^{3+}$$

C

$$Eu^{2+}$$ and $$Tb^{4+}$$

D

$$Tb^{2+}$$ and $$Tm^{4+}$$