When driving on the freeway, which of the following is an acceptable passing lane?

Answer: C — Leftmost lane

The leftmost lane, or the fast lane, is typically designated as the passing lane on the freeway. Passing on the right is usually prohibited except for limited situations such as passing slower traffic or entering/exiting the freeway. The center lane is typically reserved for merging onto and exiting the freeway, so it is not considered an acceptable passing lane. Choosing option D, which suggests that all lanes could be used for passing, is incorrect as it goes against standard traffic rules and can be dangerous.