To accurately determine the period during which the greatest volume of glacial ice was lost, one would typically refer to the data provided in the graph summarizing the changes in ice volume since 1960. Based on common trends in glacial studies, significant ice loss has typically accelerated in recent decades.
In many analyses and reports, the periods between 1980-1990 and 1995-2000 are often highlighted as times of considerable ice loss due to climate change. However, without the specific data from the graph you mentioned, I cannot definitively state the period with the highest loss.
Please refer to the graph to assess which decade shows the greatest volume loss and select the corresponding answer from the options given. If the graph shows a steep decline in a specific timeframe, that would indicate the period with the greatest loss of glacial ice.