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.