The type of flashlights (c)
<span> Sometimes a cell inaccurately duplicates its DNA, and the resulting cells are not identical.</span>
The former means those most fit, those with the best set of skills and features for the given environment, will live to pass on the said features in the offspring (with ants, for example, being incredibly fit and adaptable creatures). The latter suggests there is an objective way to measure the "meaningfulness" of each species and having only those most meaningful survive. But this differs from species to species - for a house cat, the great white shark is utterly meaningless.
Also, the meaningful animal has no actual advantage over another to help him survive, whereas fittness is exactly that - it is the ability to survive, ability to pass on your genes.
While I understand it may seem so in the case of domestic animals that the most meaningful to the human are those allowed to reproduce, it is actually the same law: those most adapted for human purpose (which, of course, in the given case means the most meaningful) ARE the fittest here in the human-controlled environment.
Radioactive dating can determine the age of minerals and fossils in each layer of rock.
Explanation:
Radioactive dating is the most commonly used geological method to determine the age of rocks and fossils layered in the layers of rock on the basis of their natural radioactive decaying.
With the help of the known rate of radioactive decay of isotopes, different types of radiometric dating are done depending upon the material found in the rock layers, like uranium-lead dating or potassium-argon dating.
Radiocarbon dating helps to record organic content in rocks like bones, shells, etc. Age of fossils sediment over sedimentary rocks is determined by combining with the bracketing method.
I think that the right answer is : The ability of a muscle to shorten in response to a suitable stimulus is called contractility.