In the seven$-$stage supplier selection and evaluation process, what differentiates a certified supplier from a preferred supplier?

a$.$

A certified supplier is no longer considered for future business until their problems are corrected, while a preferred supplier passes the buyer's initial inspection.

b$.$

A preferred supplier is one that constantly satisfies the performance and service standards defined by the buyer, whereas a certified supplier provides crucial high$-$value items to the organisation.

c$.$

Preferred suppliers are limited to a select group of suppliers who provide critical high$-$value items to the organisation, while certified suppliers consist of suppliers who no longer meet the buying organisation's standards.

d$.$

A certified supplier has had their quality systems comprehensively audited by the buying organisation while a preferred supplier has only met the purchaser s introductory screening.