A company provided income statements for the past five years. In looking at the percentage columns for each year, you notice that sales are 46 percent higher in year 5 than in year 1. The company has most likely provided
  a.  a horizontal analysis using the prior period as the base year.
  b.  a vertical analysis using sales as the base.
  c.  a horizontal analysis using year 1 as the base year.
  d.  a vertical analysis using net income as the base.
  e.  none of the above.