What is meant by "and he purifies them" (wa yuzakkīhim) in this āyah?

Imām Ibn al-Jawzī (d. 597/1201) summarized the scholars' opinions in his book "Zād al-Masīr" as follows:

1. He takes zakāh from them and purifies them with it.
2. He purifies them from shirk and disbelief.
3. He calls them to that by which they will become pure.