The right-angle on a slow-speed handpiece is held with which grasp?

The correct choice is the pen grasp when holding a right-angle handpiece in a slow-speed dental procedure. This grasp allows for optimal control and precision, as it resembles the way one holds a pen for writing. By using the pen grasp, the dental professional is able to maintain a stable grip while maneuvering the handpiece around the oral cavity, facilitating better angling and positioning for coronal polishing.

Utilizing the pen grasp also minimizes hand fatigue during procedures, making it more comfortable for the clinician, thereby improving their overall effectiveness. The other options, while they might suggest different grips, do not provide the same level of control or ergonomic benefits that the pen grasp does for this specific tool and task in dentistry.