It might be said that the purpose of this extract might be to provide an explanation on what the Iroquois considered the two different sides of human nature. The example of the twins could be stated in order to make the topic clearer by resorting to a common idea, so that everyone could be able to understand.
A dictionary contains all of this information EXCEPT parts of speech.
The participle in this sentence is <em>manufactured, </em>and since that word refers to the word <em>houses, </em>the correct answer is D) houses. The participle modifies D).