The correct answer was the 3rd most selected choice, a budget crisis. As Gregory Possehl explains "In 1931 financial problems put an end to the large-scale excavations at Mohenjo-daro. The final field season started on November 3, 1931, with Mackay planning to investigate remains to the northeast of Mound of the Great Bath. He thought there might be part of the city wall there. On the morning of November 6, he put four gangs of men to work there, but a telegram arrived from headquarters of the ASI informing him that a budget crisis demanded he cease all excavations immediately. This brought an end to the major excavations at Mohenjo-daro. Some small scale work continued there, but the big campaigns were over." (The Indus Civilization, 2002, p. 14).
Answer