he first-past-the-post, winner-takes-all system, which is used for every election in the USA - federal, state and local - makes life difficult for third parties.
Answer:
the silk was a vest trade network connecting eurasia and north africa via land and sea routes. the silk road earned its name from chinese silk, a highly valued commodity that merchants transported along these trade networks.
Explanation:
additionally buddhism , zoroastrainism, manichaeism and nestroianism were all introduced to china and parts of india because of the silk roads influence
The federal principle of government.
And federal means pertaining to or of the nature of a union of states under a central government distinct from the individual government of the separate states
I think that the key point here is the "easily reproducible" - because all of them can be scientific questions (even a! it could tell us about about the human psyche!)
but d. is the best answer for a reproducible experiment. B could also make a good experiment, but it would be too expensive to be easily reproducible. C is calling for a more complex analysis that is too complex for an experiment. And a would require more questionnaires than experiments
