Choice "D" is correct. When reporting on conditions relating to an entity's internal control observed during an audit of the financial statements, the auditor should include a restriction on the use of the report.
Choice "a" is incorrect. The auditor would not include a description of tests performed to search for material weaknesses since the auditor is not in fact obligated to search for them.
Choices "c" and "b" are incorrect. An auditor would make a statement of positive assurance on internal control and include a paragraph describing the inherent limitations of internal control in conjunction with an engagement to report on internal control. These comments would not be made when reporting on an entity's internal control in conjunction with an audit of the financial statements of a nonissuer.