Identify the correct statement from the following:

• A
  Lanthanoids have a greater tendency to form complexes than actinoids.
• B
  Actinoid contraction is greater than lanthanoid contraction.
• C
  Hydroxides of actinoids are less basic than lanthanoid hydroxides.
• D
  Binding energy of $4f$-orbitals is lower than $5f$-orbitals.