Final answer:
The term referring to an Excel Chart with offset pieces is an 'Exploded chart.' It is used to emphasize certain parts of a pie chart by offsetting slices.
Step-by-step explanation:
The term that refers to an Excel Chart with offset pieces is b) Exploded chart. In Excel, an exploded chart is often used to highlight certain parts of a pie chart by separating the slices from the main pie. This can be especially useful when you want to draw attention to specific data points or categories within the chart. For instance, if you have a pie chart showing sales by region and you want to emphasize the region with the highest sales, you could use an exploded chart to offset that piece from the rest of the pie.