Choice "B" is correct. The auditor should obtain knowledge of the client's business and its industry in order to determine the effect of transactions, events, and practices on the client's financial statements.
Choice "d" is incorrect. Constructive suggestions concerning improvements in the new client's internal control are generally made after the study and evaluation of the client's internal control, performed subsequent to planning. Knowledge about the new client's business and its industry is generally obtained during planning.
Choice "c" is incorrect. The auditor should have an attitude of professional skepticism in conducting the engagement, but this attitude is not necessarily related to the auditor's knowledge of the new client's business and its industry.
Choice "a" is incorrect. The auditor should evaluate whether the aggregation of known misstatements materially affects the financial statements, but this is done near the audit's conclusion. Knowledge about the new client's business and its industry is generally obtained during planning.