D) is your answer hope i helped
Answer and Explanation:
About two-thirds of the Earth's surface lies beneath the oceans. The depths of the open ocean were mostly a matter of speculation before the 19th century. Most people thought ocean floor was flat and featureless. In the early 16th century, a few navigators found that the open ocean can differ considerably in depth by taking soundings with hand lines, which shows that the ocean floor was not as flat as it believed.
At the beginning of the 1950s, scientists used magnetic instruments adapted from airborne devices to recognize odd magnetic variations across the ocean developed during World War II to detect submarines. They found that the iron-rich and volcanic rock make up the ocean floor-- contains a strongly magnetic mineral and can distort compass readings. In the early 18th century, this distortion was recognized by Icelandic mariners. Magnetite gives measurable magnetic properties; these magnetic variations help to study the deep ocean floor.
The two islands off the coast of Hawaii were once connected before tectonic movements.
Answer:
D) The inner portions of the disk are warm from the protostar making the heavy elements remain there.
Explanation:
So, the question is asking: why has (over the course of human history) rural settlement declined (and it is suggested that this is connected to humans moving away from the rural areas, to urban areas, rather than human population declining in general:
this process is called urbanization and its major cause is that on the one hand, food in the industrialized societies can be produced more effectively so there is less work on farm, and on the other hand the service sector has increased, which means that there is more work in the cities.