Option 1 -> Colonel Colin Mackenzie was a Scottish surveyor who first brought the ruins of Hampi to international attention during his surveys of South India around 1800.
Option 2 -> J. F. Fleet was an epigrapher who studied Hampi's inscriptions, but his work came later in the 19th century.
Option 3 -> John Marshall served as Director General of ASI in the early 20th century, well after Hampi's initial discovery.
Option 4 -> Alexander Greenlaw is not notably associated with the discovery or documentation of Hampi ruins.
Hence, Option 1: Colonel Colin Mackenzie -> He was conducting surveys for the East India Company when he documented and brought attention to the magnificent ruins of the Vijayanagara Empire at Hampi, making it known to the wider world -> correct