Opening up stegsolve, I flipped through the panes and noticed something suspicious in the top of Plane 0 for each of Red, Green, and Blue. Thus, this is probably Least Signficant Bit Steganography!  
To extract the data, I did Data Extract --> Red 0, Blue 0, Green 0 --> Save Bin.  
In the preview of the data extract, I also noticed a `PK` file header. The `PK` file header typically denotes a zip file. Thus, I decided to run `binwalk -eM` to extract all files.  
This resulted in a flag.txt in the extracted files. `cat flag.txt` gives the flag!  
    flag{what_came_first_the_stego_or_the_watermark}