An Advantage of Buying by Performance or Function Over Other

An advantage of buying by performance or function over other specification methods is that it provides:

A) the opportunity for the potential supplier to establish how to make the most suitable product/service.
B) an opportunity to purchase identical requirements from a number of different sources of supply.
C) evidence that the buyer has carefully defined the need and how it may be satisfied.
D) a standard for measuring and checking materials as supplied.
E) the potential for equitable competition by ensuring that the suppliers are quoting for exactly the same material or service.