That the application of new technology can increase the productivity of existing coal mines is demonstrated by the case of Tribnia’s coal industry. Coal output per miner in Tribnia is double what it was five years ago, even though no new mines have opened.
Which of the following can be properly concluded from the statement about coal output per miner in the passage?


A. If the number of miners working in Tribnian coal mines has remained constant in the past five years, Tribnia’s total coal production has doubled in that period of time.
B. Any individual Tribnian coal mine that achieved an increase in overall output in the past five years has also experienced an increase in output per miner.
C. If any new coal mines had opened in Tribnia in the past five years, then the increase in output per miner would have been even greater than it actually was.
D. If any individual Tribnian coal mine has not increased its output per miner in the past five years, then that mine’s overall output has declined or remained constant.
E. In Tribnia the cost of producing a given quantity of coal has declined over the past five years.

I take B, since there is no new coal mine open and output per miner was double. the only thing I can infer from those information is if a mine has increase output than its miner must also see an increase of output.

That the application of new technology can increase the productivity of existing coal mines is demonstrated by the case of Tribnia’s coal industry. Coal output per miner in Tribnia is double what it was five years ago, even though no new mines have opened.
Which of the following can be properly concluded from the statement about coal output per miner in the passage?


A. If the number of miners working in Tribnian coal mines has remained constant in the past five years, Tribnia’s total coal production has doubled in that period of time.
CORRECT
B. Any individual Tribnian coal mine that achieved an increase in overall output in the past five years has also experienced an increase in output per miner.

well no individual achievement.. We are talking about overall coal industry. It can very well possible that if say there were 10 mines, 7 of them had decline in coal output / miner but 3 of them significant increase so that the total coal output/ miner is doubled

C. If any new coal mines had opened in Tribnia in the past five years, then the increase in output per miner would have been even greater than it actually was.

Again, you can't say. it may have been a loss. we talking about industry as a whole here

D. If any individual Tribnian coal mine has not increased its output per miner in the past five years, then that mine’s overall output has declined or remained constant.

No. it can possible that his best buddy has done his, work his friend's work and the work of other two chaps, overall making a good profit

E. In Tribnia the cost of producing a given quantity of coal has declined over the past five years.

No talks about cost here.. Only output/miner...