❓ 题目 According to the passage, which of the following is a primary reason why some scientists support defining the mid-20th century as the start of a new geological epoch?
- A. The rise of agriculture and widespread deforestation created a distinct change in the rock record.
- B. Nuclear test fallout and other markers from that time are globally distributed and appear as a clear, synchronous boundary.
- C. The Holocene epoch has already ended, and a new period is necessary to describe modern climate change.
- D. Geologists have traditionally used human events rather than natural changes to define epoch boundaries.