The Precambrian time refers to the time 4.5 billion to 542 millions year ago. This period is characterized by having reduced atmosphere and included reduced compounds. Scientists believed that atmosphere at that time was devoid of free oxygen and CO2 was present in excess. Before the complex life evolved on the Earth, the Precambrian Earth's ocean contained dissolved carbon dioxide.
Your answer will be B.
Explanation:
Earthquakes are the result of released energy from tectonic plates rubbing against each other on active fault lines.
An indicator species<span> is an organism whose presence, absence or abundance reflects a specific environmental condition. </span>Indicator species<span> can signal a change in the biological condition of a particular ecosystem, and thus may be used as a proxy to diagnose the health of an ecosystem.
</span>
AIDS attacks white blood cells, damaging the immune system and making the infected individual more susceptible to illness. White blood cells are the ones that fight off harmful bacteria, so without them you could even end up in the hospital or die from a common cold.
