A wholesale dealer of stationery products plots the scatter diagram of income through the years 1985 to 2000. In which year was his income the highest?

To determine in which year the income was the highest, the wholesale dealer would need to look at the scatter diagram and identify the point with the highest income value. The year corresponding to that point would be the year with the highest income.

Without the actual scatter diagram data, it is not possible to determine the specific year in which the income was the highest. The wholesale dealer would need to refer to the scatter diagram to find this information.

The provided context does not specify the exact year in which the income was the highest. Therefore, I cannot answer this question from the given context.