224 (bonus) Answer: (c) The “queen of heaven" is a reference to an unknown false god
Read Jeremiah 44:17-25 Note: Since direct, simple answers are often the best, I want to agree with Halley. However, The Pulpit Commentary has a good argument in regard to Ishtar's "lascivious custom[s]" that can be equally applied to Ashtoreth worship. Because there are many uncertain theories about the identity of this false god it is best to say we are not sure of the identity, so this is an unknown false god.
Note: after reading the notes from several Study Bibles and Bible Commentaries I have to agree with the People’s Bible Commentary: Jeremiah/Lamentations. Like Halley, Gosdeck is direct and simple when he says, “We don’t know for sure which deity is meant." This answer, however, is overly simple. Since he gave no further explanation, I list a sampling of other opinions below.
Note: Halley’s Bible Handbook makes a quick ascertain that the queen of heaven is a reference to "Ashtoreth, the principal female Canaanite deity, whose worship was accompanied by the most degrading forms of immorality."
Note: the International Standard Bible Encyclopedia mentions Astarte, a fertility goddess in the Canaanite pantheon, because she was “an astral deity usually identified with the Assyrian-Babylonian Ishtar, who was connected with the planet Venus.”
Note: the Tyndale Old Testament Commentaries: Jeremiah and Lamentations shares a similar thought with its readers, saying the queen of heaven “may have been the Assyrian-Babylonian fertility goddess Ishtar.”
Note: the Eerdman’s Dictionary of the Bible compares and contrasts Astarte with Ishtar. In support of Astarte they mention “Phoenician inscriptions” were Astarte is referred to as “Queen.” But the problem is Astarte worship “is not known to be one in which women play a special role.” On the other hand women play a more important role in the worship of Ishtar, and “Ishtar’s cult also involves the offering of cakes called kamānu.”
Note: The Pulpit Commentary finds an objection to Ishtar since there is no suggestion of the cult’s “characteristic lascivious custom which was connected in Babylonia with the worship of Istar.”
Note: both Astarte and Ishtar are likely suspects, but doubts caused from historcal information about these goddesses and a lack of specific information that could be used to identify a particular false god from the text of the Bible leaves the question open to different interpretations.