Short answers, pulled from the story.
Chicken did not become a global staple until the 20th century. The shift from a rare delicacy to the most common meat on the planet accelerated during World War II when shortages of beef and pork forced American consumers to turn to poultry. By 1996, chicken consumption in Europe had finally overtaken that of beef and veal.
The industry has prioritized the Cornish and White Rock breeds, which dominate the American market. Modern varieties such as the Cornish Cross are hybrids engineered to maximize the ratio of feed to meat produced. These birds are bred specifically for speed and efficiency to suit industrial processing.
Manufacturers voluntarily withdrew approval for roxarsone and two other arsenic poultry drugs in September 2013. The final remaining arsenic drug, nitarsone, was banned at the end of 2015. A 2013 sample conducted by the Johns Hopkins School of Public Health found that 70% of chicken meat samples from producers that did not prohibit roxarsone exceeded safety limits set by the FDA.
Raw chicken may contain Salmonella, requiring a safe minimum cooking temperature of 165 degrees Fahrenheit to prevent illness. A 2012 survey by the Physicians Committee for Responsible Medicine found that 48% of chicken samples contained fecal matter. The bacteria survive in freezing temperatures and can grow if the food is not defrosted and reheated properly.
In the United Kingdom, juvenile chickens of less than 28 days of age at slaughter are marketed as poussin. Mature chicken is sold as small, medium, or large. In the United States, whole mature chickens are marketed as fryers, broilers, and roasters, with fryers being the smallest size at 2.5 to 4 pounds.