Answer:
The correct answer is D-semiarid
Explanation:
The Serengeti is a semiarid ecosystem producing a clearly defined rainfall gradient.
Nullify means to quiet down, or silence,so we can infer that the word nullification is made of nullif witch is a greek or latin Root. So nullification decrides t<span>he states'-rights doctrine that a state can refuse to recognize or to enforce a federal law passed by the United States Congress.</span>
Mathematics, mostly.
They also did groundbreaking work in the following fields:
Astronomy
Philosophy
Geography
Sciences
Technology
