Which of the following sentences about coal mining is an example of verbal irony? Select one: a. If you are tall, getting through the tunnel is particularly difficult because you have to bend down. b. The elevator can reach speeds of 60 mph, but most people don't notice until it starts to slow down. c. After a backbreaking day of work, the miners are rewarded with a 90-minute crawl back to the elevator. d. Travelling through the tunnel to the worksite is not considered work, so the miners are not paid for "travelling" time.