All cocks I'm afraid. Hens are more partridgey. I think Wheaton marrans can be sexed at hatching, or perhaps it was just very early? -if you do more. Although I forget the traits I used to look for, I'm sure you'll be able to Google it.
With sexing chicks at various ages its often easy to decide some obvious cocks and hens at some point, then there's some 'prob cocks, not sure' ones. I nornally let these go under the radar for far too long. I found it was best to keep the most obvious cock chick as well as any 'maybe' ones. As they age the ' maybe ones' become less like the hans and more like proper cocks, having the male bench mark makes it easier to see this.
Edited to add: just read you post, it's the black one you're asking about - sorry! She's not wheaten, may still be French marrans? Are her legs are feathered? Worth asking breeder what else they have and might have mixed eggs up with.