When a scientific experiment is carried out in a controlled setting, all variables are kept the same except for the C. experimental. Experimental variables are the things you are studying in the experiment and it is the only variable you can change.
Answer:
The inner planets are closer to the Sun and are smaller and rockier. The outer planets are further away, larger and made up mostly of gas. The inner planets (in order of distance from the sun, closest to furthest) are Mercury, Venus, Earth and Mars.
Answer: C
Explanation: The process that occurred in the lake is natural selection. In the presence of an external environmental influence such as pollution, only the trouts that were fit to survive or in other words those that have the alleles that help in adapting to the new conditions live and increased in numbers. In such a case, one can say the fittest of the organisms survived and the corresponding allelic frequency in that population increased over time. The organisms carrying the other alleles died due to pollution and hence the overall frequency of alleles change.
