The correct answer is option 4, Gandhara.

Gandhara, located in present-day Pakistan and Afghanistan, was an important region for the development of Greco-Buddhist art in ancient India. During the 1st century CE, this region came under the influence of Hellenistic culture due to the conquests of Alexander the Great and subsequent interactions with the Seleucid Empire.

Gandhara art is characterized by a fusion of Greek and Indian artistic styles. The influence of Greek art is evident in the use of realistic human figures, drapery, and naturalistic details. The Greek influence is also seen in the depiction of Buddha as a Greek god, with wavy hair and a muscular physique.

The other options, Bharhut, Bodh Gaya, and Sanchi, are significant sites in Indian art and architecture but do not have direct Graeco-Roman influence. Bharhut is known for its early Buddhist stupas, Bodh Gaya is the site of the Mahabodhi Temple where Gautama Buddha attained enlightenment, and Sanchi is famous for its Buddhist stupa and intricate stone carvings.