Determine whether the following statements are True $(T)$ or False $(F)$:
$(a)$ Transition elements contain $d$-orbitals.
$(b)$ Ions of transition elements contain incompletely filled $d$-orbitals.
$(c)$ Only elements with completely filled $3d$ orbitals are considered transition elements.
$(d)$ Only elements that have incompletely filled $d$-orbitals in their ground state as well as in their ions are called transition elements.

• A
  $(a) T, (b) T, (c) F, (d) T$
• B
  $(a) T, (b) T, (c) T, (d) F$
• C
  $(a) F, (b) T, (c) F, (d) T$
• D
  $(a) T, (b) F, (c) F, (d) T$