[单选题]
A country's year-end consumer price index over a 5-year period is as follows:
Year 1 106.5
Year 2 114.2
Year 3 119.9
Year 4 124.8
Year 5 128.1
The behavior of inflation as measured by this index is best described as:
A.deflation.
B.disinflation.
C.hyperinflation.