If a micrometer were opened to a distance of 0.0001 inch, you would say the reading is __________.

Correct Answer: Option C — one ten thousandth of an inch

A standard machinist's micrometer is graduated such that each graduation on the thimble represents 0.001 inch. When the thimble is divided into ten parts by a vernier scale, each mark represents 0.0001 inch, which is defined as one ten-thousandth of an inch, the standard precision for mechanical measurements.