Quality screw threads are produced by

Answer: Option B

Thread chasing is the method used to produce quality screw threads with high accuracy and good surface finish.

Reason: In thread chasing, a chasing tool or die head is used, which accurately guides the cutting edges to follow the correct thread profile, ensuring precision.

Other methods:
Thread milling is suitable for large threads but not as accurate for precision threads.

Thread cutting with a single point tool is common for general purposes but does not produce high-quality threads due to tool deflection and slower operation.

Thread casting is used for bulk production but results in poor accuracy and finish, requiring further machining.

Conclusion: For accurate and high-quality screw threads, the correct method is thread chasing.