Lucent Wish

Am I correct in understanding that any photo/image that a participant likes is acceptable?

Yes.
If you're curious and have the time, you can check out similar contests from previous years (links in the first post).

Even if you wrote, "The contest was chosen as a result of discussion and democratic choice by the participants. Ripped pants are migrating south," it wouldn't be much less understandable! What does the last sentence mean?

The moderator is right about the last sentence; otherwise, it doesn't carry any semantic weight.

Does the picture have to match the song?

Well, yes, but I'm more interested in how you prefer to evaluate: purely visually/by ear, based on synergy, or in some other way.

If you can't decide on the ninth entry, I'll do something myself according to my own judgment.