I got an email about meal selection on a ATL-FRA flight next week. I am in C+. I haven't flown DL long-haul in years, so I don't know if this is an example of this.
I was given two choices - a pasta (vegetarian, I think) and a chicken option. The email didn't work - after clicking my selection, I got a "sorry about that" link. Didn't work on either a phone or desktop web.
I called in for fun, and was told that phone agents are only able to handle special meals, not ordinary meals.

I am guessing that it's the same meals as Y, but Delta is trying to give C+ first choice - and, big surprise, still hasn't worked out the IT kinks.