Which of the following activities is a form of error-proofing?

Error-proofing, or "poka-yoke," is a technique used to prevent errors by designing processes, equipment, or fixtures to avoid mistakes.

Fixture design involves creating jigs, fixtures, or tooling that ensure parts are correctly positioned and assembled, thereby preventing errors.

Housekeeping, equipment calibration, and double sampling do not inherently prevent errors by design.

References: The concept of error-proofing is detailed in quality engineering literature, such as "Poka-Yoke: Improving Product Quality by Preventing Defects" by Shigeo Shingo.