The avenues in a particular city run north to south and are numbered consecutively with 1st Avenue at the western border of the city. The streets in
the city run east to west and are numbered consecutively with 1st Street at
the southern border of the city. For a festival, the city is not allowing cars to
park in a rectangular region bordered by 5th Avenue to the west, 9th Avenue
to the east, 4th Street to the south, and 6th Street to the north. If x is the
avenue number and y is the street number, which of the following systems
describes the region in which cars are not allowed to park?