What these photos are rejected?

All are underexposed and not well composed. The second one would need model releases for all of the recognizable people in the image, including the ones with their backs turned.

Your images must be suitable for commercial use in print, digital or merchandise

• https://helpx.adobe.com/stock/contributor/help/reasons-for-content-rejection.html
• https://helpx.adobe.com/stock/contributor/help/quality-and-technical-issues.html
• https://helpx.adobe.com/stock/contributor/user-guide.html/stock/contributor/help/photography-illustrations.ug.html
• https://helpx.adobe.com/stock/how-to/tips-stock-image-acceptance.html
• Model/Property Releases:
  https://helpx.adobe.com/stock/contributor/help/model-release.html
  https://helpx.adobe.com/stock/contributor/help/property-release.html
  
  

Below, I used Photoshop to add a Levels Adjustment Layer to balance shadows & highlights.

The left half is your original, the right half shows adjustment.

All of the photos have exposure issues.

The first needs an IP release and is poorly cropped.

The second needs IP and model releases.

The third is poorly cropped and probably has no commercial value.

What was the rejection reason? I would guess quality, but there may also be IP reasons to reject each of your assets. And your second one needs also model releases for each of the recognizable people. 

(1) probably model release needed.

(2) IP violation, edit out (or get a property release).