Oral rehydration salts are used to prevent and treat dehydration, especially that due to diarrhea.
Answer:
for the environment biking
for overall speed airplanes for long distances
The second largest city in Brazil is Rio de Janeiro, while the third biggest is the capital Brasilia. Rio de Janeiro has an estimated population of around 6,5 million people while Brasilia has little less than 3 million. This makes Rio de Janeiro more than twice bigger in population than the capital of Brazil, Brasilia. But there's something interesting in here in the background, in the past 6 years the population of the second Rio de Janeiro has only increased by little over 9%, while Brasilia's population has increased by around 20% which is more than twice in increase, so if that trend continues in the coming few decades Brasilia will come on top of Rio de Janeiro very quickly.
D because that describes exactly how they are made