Problem: Matryoshka dolls are a set of wooden dolls of decreasing size placed one inside another. What’s the final one? Image: this

File: THE_FILE

Solution:

binwalk dolls.jpg -Me

Like the name implies, the image has zip files within it eventually after unzipping it all you get a file marked: flag.txt

cat flag.txt

picoCTF{4cf7ac000c3fb0fa96fb92722ffb2a32}

Flag: picoCTF{4cf7ac000c3fb0fa96fb92722ffb2a32}