Who is being referred to "those who were given the Book" in this āyah?

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

1. The Jews. [Muqātil]
2. Both the Jews and the Christians. [Abū Sulaymān al-Dimashqī]