Corvids are a large family of birds that includes many species of ravens, jays, crows, and magpies. It was recently discovered that numerous birds in this family are an important vector for the West Nile virus because infected mosquitoes may pass the virus to these birds. Not to mention other species: there are over 35 species crows across the world alone and more than 3,500 species of mosquitoes across 41 different genera. Taken together, these facts demonstrate that it is critical that global societies and scientists a) use more detailed common names to identify species, such as the "violet crow" or the "American crow."
b) use the genus and specific epithet scientific name to identify taxa.
c) use DNA sequences when referring to a particular species.
d) track diseases like West Nile virus using remote sensing technology on birds to help predict illness spread.
e) invoke higher levels of the classification system, such as kingdom and domain, when referring to a species.

the answer can be found on g o o g l e

americans began to notice growing differences between the northern and southern sections of the country. there were more people living in cities in the north, which made it more urban. more people lived on farms in the south, which made it more rural. while many people were farmers in the northern states, there were now other ways to make a living, such as working in mechanical cotton gins factories manufacturing cloth, tools and other goods. people in the north supported high tariffs on goods imported from europe because the extra cost encouraged people to “buy american” instead. in the southern states, planters did not like tariffs because they sold most of their production to europe and bought their tools from there as well. southerners believed the protective tariff was something that only northern factory owners keep their profits high. so the southern politicians came up with an idea. they would opt out. they would simply ignore the protective tariff. it was ‘null and void’ in south carolina. the state would not collect the taxes on goods imported into south carolina, no matter what the president said they had to do. this decision led to the nullification crisis.

substitution is the answer in this case