Final answer:
The correct answer is that a CPA must monitor and ensure that third-party providers follow relevant professional standards when they use their services.
Step-by-step explanation:
If a CPA in professional practice employs the services of a third party provider, the CPA should monitor and ensure that the third-party provider follows relevant professional standards. This means choice d) A CPA should monitor and ensure that the third-party provider follows relevant professional standards is correct. While working with third-party providers, CPAs must ensure that those providers adhere to the same ethical and professional standards that apply to the CPAs themselves. This responsibility cannot be outsourced, and CPAs must conduct due diligence and ongoing monitoring of the third-party's work.