$8.$ Given the business examples below, state what type of market structure each example describes.

a$.$ Two lemonade stands on the same neighborhood block.

b$.$ A water$-$treatment plant in Denver, Colorado.

c$.$ A bookstore on the Auraria campus.

d$.$ Grocery delivery services.

e$.$ Subaru mechanics located in the inner city.

f$.$ The Boulder farmer$$s market.