The action from The Jungle Book that best supports the claim that Baloo used the Law of the Jungle to save Mowgli is:
Baloo speaks up for Mowgli at Council Rock.
In this scene, Baloo advocates for Mowgli's right to belong to the jungle and emphasizes the importance of his place in the animal community, illustrating his commitment to the principles of the Law of the Jungle to protect and support Mowgli.