Explanation: Transition elements are those which have electrons in the d orbitals in their outermost valence shell. They are also known as d block elements.
Thus Copper, Iron, Nickel etc are d block elements because their electrons are in the d orbital as shown-
Copper (Cu) = [Ar] 3d10 4s1
Iron (Fe) = [Ar] 3d6 4s2
Nickel (Ni) = [Ar] 3d8 4s2
Thus as shown in the electronic configuration above, the given stateent is true.