Answer: "(a) Frames and tires used in manufacturing bicycles" - Direct materials.
"(b) Wages paid to production workers." - Direct labor.
"(c) Insurance on factory equipment and machinery." - Manufacturing overhead.
"(d) Depreciation on factory equipment." - Manufacturing overhead.
Explanation: Direct materials are all those that are used directly in the production of a good or service.
Direct labor is that directly involved in the production of a good or service.
Manufacturing overheads are all those expenses that, although necessary for the production of a good or service, are not directly involved in the production process.