I. Income in 1985 = 20,000
Income in 1995 = 64,000 (approx.)

Klein family's annual income more than doubled from 1985 to 1995 can be inferred.

II. Income in 1990 = 38,000 (approx.)
Income in 1985 = 20,000
income increased by = 18,000 (approx.)

Income in 1995= 64,000 (approx.)
Income in 1990 = 38,000 (approx.)
income increased by = 26,000 (approx.)

The Klein family's annual income increased by a greater amount from 1985 to 1990 than from 1990 to 1995 cannot be inferred

III. Average is difference of all the readings below the average is equal to difference of all the readings above the average.
Analysing visually, average for the period shown should be greater than $40,000
average (arithmetic mean) annual income for the period shown should be greater than $40,000

The Klein family's average (arithmetic mean) annual income for the period shown was greater than $40,000 can be inferred.

IMO C