Mountain hillsides is the answer<span />
They study landforms and its caracteristics such as elevation, slope, orientation, stratification,<span> rock exposure, and soil type because can be a mineral deposits or can give some information about fossils. </span>
In the African countries where HIV/AIDS is a big problem the economies have big problems. People that have it are usually young people, they lack the physical power and the concentration to be effective workers, or they can not work at all, and this affects the economy because the efficiency is very low or non existent from the people that have HIV/AIDS. Also, this means that this people need medical care, an expensive one, and they usually do not have the resources to pay for it, so the governments spend big amounts of money on this as well.
The correct answer is D. Small nations are less active in world trade.
Explanation
Oceania is a continent made up mainly of islands, among which Australia and New Zealand stand out internationally. However, the rest of the countries are very little known internationally and do not actively participate in trade because they do not have large industries, nor are they sources of natural resources. These islands are mainly considered tourist destinations for their tourist attractions. Therefore, the correct answer is D. Small nations are less active in world trade.