高手 看一下啊

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?

• AIf 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.  这题目选A   in the past 5 years  和  原文的 it was five years ago是一个意思么怎么读起来总有种  in the past 5 years  是一个范围  就是  在过去的5年里                 five years ago是 5年前的一个时间点呢？
  文章说 产量提高是因为科技上去了    每个矿工煤的生产量   要是  5年前的2倍多   即使没有新矿建立
•     A选项说如果矿工数量不变在过去的5年里      T城市的总煤产量  是 该阶段的2 倍
  刚做这个题就感觉  原文定位到 现在的平均产量  和5年前的平均产量       而A选项 说的是 过去5年每年的人数  好像有点不对等的感觉。。就没选 结果错了。。。

我想问问 是不是我理解错了这两个时间状语的意思了呢 还是理解错句意了