A cylindrical square is capable of checking units as precise as:

A cylindrical square is a precision tool used in machining and engineering to ensure that parts are held at a perfect right angle and to check the alignment of surfaces. The ability of a cylindrical square to check units with precision depends on its construction and the manufacturing tolerances associated with it.

The answer provides a precision of 0.0002 inches, which indicates a very fine tolerance level. This level of precision is suitable for high-accuracy applications, such as machining and manufacturing processes where even minuscule deviations can lead to significant issues in the final product. This is particularly important in industries that require tight tolerances for proper functioning and fitting of mechanical components.

In comparison, the other options offer less precision, which may be adequate for less demanding applications but not suitable for scenarios where extreme accuracy is critical. Therefore, the correct answer highlights a level of precision that standard cylindrical squares can achieve in professional settings, reinforcing the importance of precision in technical fields.