Answer:
The hardness rating is 4.
Explanation:
Calcite sits at a hardness rating of 3 and is very easily scratched with a knife and/copper coin. This is where most Marbles, limestones, travertines, rate.
Meanwhile, Fluorite sits at hardness 4 and can be scratched by a knife.
Charles Darwin noticed that among the same species there were variations in traits based upon geographical location. These changes may have evolved from climate differences, predator/prey relationships and food sources. This particular experiment was intended to duplicate natural selection by demonstrating the concepts with artificial selection. The result was that over time, new traits could be bred for. Although there may be more than one correct answer here, the best answer is the first; desirable traits can be selected and bred in offspring.
The largest animal in the world is the blue whale
