Which of the following is a soup served on Fridays?

The correct choice highlights clam chowder as a soup served on Fridays. This distinguishes it as a specialty offering that showcases the restaurant's menu diversity. Clam chowder is often celebrated for its rich flavors and creamy texture, making it a popular choice among customers who appreciate hearty soups, especially when it's part of a special day’s selection.

The other soups listed hold their own appeal; however, they may not be specifically associated with Friday service or may be offered on different days of the week. For diners familiar with the Portos Menu, recognizing clam chowder as a Friday offering helps in understanding the consistent theme of the restaurant's meal planning and customer preferences. This element of the menu highlights how certain dishes can be tied to specific days, fostering anticipation among customers.