Which of the following includes four important internal control procedures?

a.independent review and appraisal; design and use of business documents; rotating independent auditors every year; safeguarding of assets and records

b.independent verification; proper authorization; the audit committee reporting to the controller; safeguarding of assets and records

c.proper authorization; segregation of duties; background checks on all employees every month; independent verification

d.proper authorization; segregation of duties; independent verification; safeguarding of assets and records