According to the data, in which year did the population of zebra mussels show a decrease that is most likely the
result of a decrease in the availability of a source of
food?
A
1997
B
2002
с
2008
D
1993

is in 1997 the population of zebras mussels show decreases

well stockyards mean a large yard containing pens and sheds, typically adjacent to a slaughterhouse, in which livestock is kept and sorted. and i'm assuming that by party you   mean a large group of people which does make sense because chicago is a very crowded place much like new york. stockyards tend to take up a lot of room due to needing the area for pens to keep animals in and the fact that stockyards are usually right by slaughterhouse where they process and distribute the product. so its much like a zoo but with some dead animal products close by.