Which of the following statements is true regarding electrons in transition metals?

Electrons in transition metals exhibit unique characteristics due to their position on the periodic table, which allows them to have varying numbers of electrons involved in bonding and oxidation states. The key feature of transition metals is their ability to lose different numbers of electrons from their outer shell. This is because the d-orbitals, which are filled after the s-orbitals, can participate in bonding and can also overlap with the s-orbital electrons.

Unlike main group elements, which often have a fixed number of valence (outer) electrons, transition metals can show oxidation states typically ranging from one to three, and sometimes even more in certain compounds. This variability is primarily due to the involvement of d-electrons as well as s-electrons in chemical reactions and bond formation.

Thus, the statement about transition metals having between one to three outer electrons accurately reflects their flexible electron configuration and allows for various chemical behaviors, confirming its truthfulness.