Why would it be important to have a true representative sample when talking about public opinion ?

they are best described as reliable search engines.

a system of cooperative federalism emerged, as the powers of the federal government expanded.

the correct answer is b.

the british invasion was also known as "english wave", was the predominant musical trend in the united states in the mid-60s, when numerous groups ofss rock & roll that were originally from the united kingdom, reached high levels of popularity beginning with the success of the beatles in north america. all these groups, clearly influenced by rock & roll, blues and american rhythm & blues, were able to elaborate simple songs

and catchy. in the middle of 1962 the rolling stones began like one of a series of groups that show more and more influence, along with bands like the animals and the yardbirds. in 1963, the beatles and other rhythm groups, such as the hollies, had achieved great popularity and commercial success in britain itself. the british rock received a pass to the popularity of musical currents in the united states in january 1964 with the success "i want to hold your hand" ranked number 1 on the billboard hot 100 list, beginning the british invasion of the music list of the united states.

also musical genres influenced by african rhythms such as soul, began to have popularity.

many of the best musicians in history are english: the beatles, queen, pink floyd, bowie, the smiths, led zeppelin.