In a doughnut chart, you can pull out only the slices of the outer ring.
To pull out only one slice in a pie chart, click the pie, click the slice you want to move, and then drag the slice away from the center of the chart.
To pull out only one slice in the outer ring of a doughnut chart, click the outer ring, click the slice you want to move, and then drag the slice away from the center of the chart.