Photos rejected for quality issues

Stock isn’t an art/photo gallery. It’s a global assets service for professionals to source commercial-ready content for use in print, digital, web and merchandise.

Adobe doesn’t typically accept duo-tones or monochromes. See photography Dos & Don’ts. 

https://helpx.adobe.com/stock/contributor/submit-your-content/submit-photos/photo-editing-best-practices.html

Examine images closely at 100-300% magnification. Also refer to your histogram panel to ensure balanced exposure in highlights, midtones & shadows.

Customers prefer clear, natural, high resolution images. 

Hope that helps.

Hello,

Composition is the major issue I see. Composition is really important when taking photos. You could have everything else right, but if the composition is bad, then the photo loses its power!

When taking land and sky shots, try not to divide the picture in half!

Your beach shot is underexposed - it's just a bit too dark!

Adobe has some advice on composition:

Composition

The two bottom images are split in the middle. Consider using the rule of thirds when it comes to landscape in particular. In the middle photo, the sky is less interesting that the foreground, so more of the foreground should have been included. In the bottom one, the sky is more interesting and than the large area of beach in the foreground. The horizon line is also slanted a bit.

The top photo is underexposed, and its white balance is excessively skewed.

While the two photos below look nice, their composition is uninteresting.
Photos of the sea are submitted in very large numbers.
If there are any issues—such as with composition, exposure, or a tilted horizon—the photo will be rejected immediately.
Even if there are no apparent flaws, it may still be rejected.
Because so many such photos have already been submitted, I suggest looking for a different theme.

I don’t know how much i can comment for your photo. you really got nice picture

​@glamorous_hope6450 
Let’s take the middle image… The image is cool. I love the concept and idea. If there were a single set of foot prints leading to the beach this could be marketable. There are too many footprints. A single set of footprints would lead my eye to the beach for example. 

I would take a few minutes and clean up the image as well. Bump up the colours, remove a few unwanted bits, and sharpen the image.

Nate