For the next few questions, consider the perfectly competitive market for chicken sandwiches sold between 3 pm and 4 pm in the Five Points Shopping area.

a) Define a perfectly competitive market and its characteristics.
b) Why is the time frame specified (3 pm to 4 pm) important in this market scenario?
c) How does competition impact the pricing and quality of chicken sandwiches in this market?
d) Discuss one factor that could lead to a shift in supply or demand for chicken sandwiches during this time period.