Final answer:
The Rosetta Stone was the tool that helped decipher Egyptian hieroglyphics by comparing it with the Greek text.
Step-by-step explanation:
The tool that helped researchers decipher Egyptian hieroglyphics was The Rosetta Stone. The Rosetta Stone is an ancient artifact that contains a decree issued in three different scripts: ancient Egyptian hieroglyphics, demotic script, and Greek. By comparing the Greek text, which was already understood, with the hieroglyphics and demotic script, scholars were able to decode and understand the meanings of the hieroglyphics.
Learn more about Deciphering Egyptian hieroglyphics