Which of the following is a true statement about activity-based supplier costing?
  a.  The cost of a supplier is the purchase price of the components or materials acquired.
  b.  Suppliers can affect many internal activities of a firm and significantly increase the cost of purchasing.
  c.  It encourages managers to evaluate suppliers based on purchase cost.
  d.  It encourages managers to increase the number of suppliers.
  e.  All of the above are true.