Final answer:
Transesophageal pacing is the mode that can only provide pacing of the atria and not the ventricles of the heart, while the other options can pace both chambers in different ways.
Step-by-step explanation:
The modality that can only be used to provide pacing of the atria of the heart and cannot be used to pace the ventricle directly is Transesophageal pacing. It involves placing an electrode in the esophagus, which is close to the left atrium, and can stimulate atrial contraction but is not suited for ventricular pacing. The other options listed, such as Transcutaneous (temporary pacing through the skin), PA catheter (which may be used for monitoring rather than pacing), and Epicardial (which refers to pacing leads placed directly on the heart during surgery), can be used to directly or indirectly affect both atrial and ventricular rhythms depending on specific methods employed.