Choice "B" is correct. The paragraph presented is the proper form of disclosure when another auditor performs a substantial portion of the audit. When the group engagement partner makes reference to the audit of another auditor (component auditor), the report should indicate clearly the division of responsibility between the portion of the financial statements covered by each audit.
Choice "a" is incorrect. By making the disclosure that another auditor (component auditor) performed part of the audit, the group engagement partner explicitly does not assume responsibility for the component auditor's work. If the disclosure is omitted, then the group engagement partner implicitly does assume responsibility for the component auditor's work.
Choice "c" is incorrect. Reference in the report of the engagement team partner to the fact that part of the audit was performed by another auditor (the component auditor) is not a qualification of the opinion. It is simply an indication of the divided responsibility between the auditors who conducted the audits of various components of the overall financial statements.
Choice "d" is incorrect. The paragraph presented is the proper form of disclosure when a component auditor performs a substantial portion of the audit.