The overall specific gravity of the earth is much higher than the specific gravity of crustal rocks which means the earth is about twice as heavy as the rocks on the surface would suggest. Iron meteorites are thought to have the same composition as the average earth, and the meteorites contain a lot more iron than the Earth's surface rocks.
Answer:
During construction habitat destruction may occur where a habitat is removed to make way for a new development. Plants and sessile animals in these areas are usually directly impacted generally resulting in alteration or reduction in biodiversity.
First, there were two independent clinical psychologists who were present or on call 24 hours a day. They had the power to intervene and to remove anyone from the study if they thought they were in distress.
Second, we had paramedics and security guards on hand and ready to intervene at a moment’s notice if anything untoward happened in the study.
Third, the study was constantly monitored by members of a five-person independent ethics panel. This was chaired by a Member of Parliament and also included members of the Holocaust Educational Trust, the Howard League for Penal Reform, the BBC’s Independent Editorial Policy Unit and a senior academic psychologist. This committee had the power to change the way the study as a whole was run and to terminate it if they had ethical concerns.
http://www.bbcprisonstudy.org/bbc-prison-study.php?p=27
The answer may be B, but i may be incorrect.