Over the course of the 20th century, humans have become increasingly more vulnerable to the disruption of commerce caused by volcanic eruptions.
Which change has most increased the vulnerability of commerce to volcanic eruptions?
O A. The frequency and intensity of volcanic eruptions have increased.
B. The pollutants released by volcanic eruptions have become more toxic.
O C. The overall amount of commerce conducted by alr transportation has increased.
D. The overall amount of commerce conducted by ground transportation has increased.