Donaldson & Moss, CPA's provides various nonattest services to its attest clients. The firm only wants to provide such nonattest services that do not impair its independent with respect to the firm's attest clients. Which of the following nonattest services would impair the firm's independence with respect to an attest client?

a. Using payroll time records provided and approved by the client to process a client's payroll and produce unsigned payroll checks for the client to sign.

b. Assist in developing corporate strategies.

c. Provide assistance in assessing the client's business risk control process.

d. None of the above would impair the firm's independence.

e. Both a. and c. would impair the firm's independence.