Workers are usually exploited when the employers can benefit from it financially, that is when there are <span>a. there were more workers than jobs and they don't have to be afraid of loosing workers- they can then force them to work more for the same pay.</span>
metallurgy is your answer
The "study of metals and the process of refining (them)...."
Note that it says metal. Metallurgy has the word "Metal" in it, and so is most likely your answer (and is your answer).
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Answer:
they made transportation faster
Explanation: