The UV-visible absorption bands in the spectra of lanthanoid ions are primarily influenced by the electronic transitions that occur within the f orbitals. Lanthanoid ions have partially filled 4f orbitals, and the transitions within these orbitals are generally quite narrow. This is because the 4f orbitals are well shielded by the outer 5s and 5p orbitals, which results in minimal interaction with the surrounding crystal field, leading to narrow absorption bands.

Therefore, the correct answer is:

Option B: Narrow and f orbitals