Questions & Answers about dono e ga suki desu ka.
Yes, どれが好きですか could work if it is already clear that you are choosing from pictures.
But 絵 is included when the speaker wants to specify the category clearly: which picture.
So the difference is roughly:
- どれが好きですか。 = Which one do you like?
- どの絵が好きですか。 = Which picture do you like?
Japanese often leaves out words when the context makes them obvious, but including 絵 makes the question more specific.
