Who of the following had first deciphered the edicts of Emperor Ashoka?

The answer is James Prinsep. As Secretary of the Asiatic Society of Bengal, he deciphered the Brahmi script in 1837, which opened up the Ashokan edicts. He also recognised that the title 'Piyadasi' used in them was an epithet of Ashoka, and that 'Devanampiya' was a royal honorific.

• Georg Buhler is wrong. He was a major epigraphist and Indologist, but he worked after Prinsep's breakthrough. He is known for editing Sanskrit texts and for the Sacred Books of the East series.
• Max Muller is wrong. He was a philologist who edited the Rig Veda and worked on comparative religion. He did not decipher any inscription.
• William Jones is wrong. He founded the Asiatic Society in 1784 and linked Sanskrit with Greek and Latin. He also identified Sandrocottus with Chandragupta Maurya, but he did not read Ashokan script.

The core concept is epigraphy as a source of ancient history. Prinsep's work is why the Rock Edicts can be used in GS-1 answers on Ashoka's Dhamma, the spread of Buddhism and the Mauryan state.

Trap: Aspirants often credit Buhler or Jones because they are more prominent names in Indology. Remember that the decipherment of Brahmi came first, in 1837.