Which of the following cannot form complex compounds ?

Si,Ge,Al forms complex compounds, due to the presence of empty d-orbitals in their valency shellEx:-Si → [SiF6]-2Ge → [GeF6]-2Al → [Al(H2O)6]+3Carbon can't forms complex compounds due to lack of empty d-orbitalsDue to lack of empty d-orbitals it can't have the ability to accept electron pair from ligands [Lewis bases]