The owner of a Stoughton shopping plaza said his company is considering “all options” after one of its key tenants closed. The Shaw’s Supermarket at 666 Washington St. officially closed on Aug. 3, one of six Shaw’s stores closed in the area this summer. The Stoughton supermarket employed more than 100 people, according to the Massachusetts Labor and Workforce Development website, and was located on land owned by Coolidge Properties of Brookline. “We are disappointed that the new Shaw’s ownership group did not show more of a commitment to turning this location around,” said Jeff Vecchio, vice president of the firm. “We are confident that with the right management in place this is a very viable site for another grocer.” Shaw’s still has a supermarket in the Cobbs Corner Village Shoppes in Canton, just over the Stoughton line.