Correct option is D
A V-block is the best device for holding and locating a round bar securely during drilling, milling, or inspection. It consists of a V-shaped groove that firmly supports cylindrical workpieces, preventing movement and ensuring accurate positioning while machining.
V-blocks are commonly used in tool rooms, machining, and quality inspection to hold round parts securely while measuring, marking, or drilling. They often come with clamps to keep the workpiece stable.
