Which machine is specifically used to harvest grain and may thresh and clean the grain in one operation?

• A. Combine
• B. Harvester
• C. Reaper
• D. Threshing machine

Answer: (A)

The key idea is that this machine combines three harvest steps into one pass: it cuts the standing grain (reaping), threshes the grain from the heads, and cleans the grain from chaff. That integration is why it’s the best answer for a device used to harvest grain and may thresh and clean in a single operation. The reaper only cuts; a threshing machine separates grain from the straw but doesn’t cut the crop in the field; and while harvester is sometimes used loosely, it doesn’t inherently perform all three steps in one go as a combine does.