Which of the following characteristics of lanthanides is correct ? 

In Lanthanides, the atomic size of elements reduces from La to Lu due to Lanthanide contraction. This depicts that reducing property also decreases from La to Lu.

Because of having small atomic size and high charge density, the tendency of forming complexes increases from La to Lu.

From La to Lu, the size decreases and the covalent character increases, thereby the basic character decreases.

Lanthanides attain +3 oxidation state by loosing two 6s electrons and one 4f electron.