Choice "A" is correct. An auditor's engagement letter typically includes discussion of limitations of the engagement, such as the fact that the auditor will obtain only reasonable assurance, and therefore a material misstatement may remain undetected.
Choice "c" is incorrect. An auditor's engagement letter typically covers the objectives of the engagement, management's responsibilities, the auditor's responsibilities, limitations of the engagement, and other matters involving the conduct of the audit. Potential significant deficiencies discovered during the prior year's audit would not typically be included in the engagement letter.
Choice "d" is incorrect. While the auditor's engagement letter might include a discussion of the overall audit strategy, it typically would not include specific audit procedures.
Choice "b" is incorrect. While the auditor's engagement letter might include a discussion of the auditor's responsibilities, this is usually discussed in fairly general terms. An engagement letter would not describe the auditor's responsibility with respect to specific issues (such as going concern issues).