One of the ideas behind colonization was to create a new workforce that was
a. more skilled.
c. more creative.
b. cheaper.
d. easier to control.

Colonisation brought with it a lot of cheap labour that could be forced to work under the threat of a prison - so it's not about more skilled or more creative workforce.

Both other options are correct, but "cheaper" is the more important one- some of the work force would be enslaved so would work for free.

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