Which statement describing the stock market system is true? a. a stock exchange is a person who sells shares of stock to the general public. b. a period when all companies' stocks are losing value is called a "boom." c. the value of a share of stock can never fall below its original purchase price. d. many companies sell stock to finance an expansion of their businesses.

genetics is the study of how dna works, the methodologies defining the new recent technologies allow scientist to have a panoramic view of the entire dna landscape, especially how genomes interact with their environment, including off course, factors outside their organisms.

thus is very possible the existence of both scenarios, where populations of isolated individuals have different genetic traits, and share traits related to genetic mutation, due rats can easily travel overseas using human transport channels. so scientists could get a vast number of data, including human interaction, evolution of rodents, health development, spread of infections, development of new organisms, how genomes evolve in different environments and so on.