Which of the following tool is used to check the roundness and cylindrical accuracy of a component?

The question asks to identify the tool used to check the roundness and cylindrical accuracy of a component.

• A) Vernier Caliper: Primarily used for general linear measurements, including external and internal diameters, and depth. While it measures diameter, it is not ideal for precise assessment of roundness or cylindrical accuracy.
• B) Micrometer: Used for highly precise linear measurements, such as external, internal, or depth dimensions. Similar to a Vernier caliper, it measures diameter but is not the primary tool for evaluating geometric tolerances like roundness or cylindricity.
• C) Dial Gauge: A dial gauge, often used in conjunction with a stand or fixture (e.g., a run-out stand or a bore gauge), is specifically designed to measure small variations in a surface. It is highly effective for checking geometric tolerances such as run-out, flatness, and roundness or cylindrical accuracy by indicating deviations as a component is rotated or moved.
• D) Feeler Gauge: Used to measure small gaps or clearances between two parts. It is not used for measuring dimensions or geometric accuracy like roundness.

Among the given options, the Dial Gauge is the most suitable tool for checking roundness and cylindrical accuracy.

The final answer is $\boxed{\text{C}}$.