Question: Which West Coast pizza chain could I visit if I went to Northern California, Mountain Mike's Pizza or Dion's? 

Context paragraphs:
Mountain Mike's Pizza: Mountain Mike's Pizza is a chain of pizzerias mainly along the West Coast of the United States, primarily Northern California.  They have additional locations in Nevada, Oregon, and Utah.  The restaurants offer other items, such as pasta and chicken wings.

Pizza California: Pizza California (ピザ・カリフォルニア , Piza Kariforunia ) is a pizza chain in Japan.  Franchises of the chain are located in 26 of Japan's 47 prefectures.  The company has its headquarters in the Hiei Kudan-Kita Building in Kudankita, Chiyoda, Tokyo.

Blackjack Pizza: Blackjack Pizza is a Colorado-based pizza delivery chain founded in 1983 by a former Domino's Pizza employee, Vince Schmuhl, because Domino's Pizza was the only major pizza delivery company in the Rocky Mountain region and he thought customers would appreciate an alternative.  The pizza chain is the largest in Colorado with 800 employees, some of whom work part-time.  On January 1, 2013, Blackjack Pizza was acquired by Askar Brands.

Extreme Pizza: Extreme Pizza is a privately held restaurant franchise chain specializing in conventional and California-style pizza, founded by Todd Parent and Michael Pastor in 1994 in San Francisco, California.  The chain currently includes over 30 locations in the United States, and one in Ireland.  Most franchises are located in Northern California, as well as other states including Colorado, Texas, Virginia, Washington, Oregon, Idaho, and Michigan.

ARCO: Atlantic Richfield Company (ARCO) is an American oil company with operations in the United States, Indonesia, the North Sea, and the South China Sea.  It has more than 1,300 gas stations in the western part of the United States.  ARCO was formed by the merger of East Coast–based Atlantic Refining and California-based Richfield Oil Corporation in 1966.  A merger in 1969 brought in Sinclair Oil Corporation.  It became a subsidiary of UK-based BP plc in 2000 through its BP West Coast Products LLC (BPWCP) affiliate.  On August 13, 2012, it was announced that Tesoro would purchase ARCO and its refinery for $2.5 billion.  However, the deal came under fire due to increasing fuel prices.  Many activists urged state and federal regulators to block the sale due to concerns that it would reduce competition and could lead to higher fuel prices at ARCO stations (ARCO stations make up more than half of all stations with the lowest fuel prices in California).  On June 3, 2013, BP sold ARCO and the Carson Refinery to Tesoro for $2.5 billion.  BP sold its Southern California terminals (Vinvale, Colton, San Diego, Hathaway, and Hynes) to Tesoro Logistics LP, including the Carson Storage Facility.  BP will continue to own the ampm brand and sell it to Tesoro for Southern California, Arizona, and Nevada.  BP exclusively licensed the ARCO rights from Tesoro for Northern California, Oregon, and Washington.

Dion's: Dion’s is a privately owned chain of pizza restaurants based in Albuquerque, New Mexico.  As of 2017 Dion’s operates 23 restaurants; 18 in New Mexico, 2 in Texas, and 3 in Colorado.

Apache Pizza: Apache Pizza is a chain of fast food pizza delivery restaurants in Ireland.  Founded in 1996 by Emily Gore Grimes and Robert Pendleton, Apache is the trading name of The Good Food Company.  As of 2016, there are 139 stores across the Republic of Ireland and nine stores in Northern Ireland.  Apache is Ireland's largest pizza chain.  Its Managing Director is Robert Pendleton.

Chicago Franchise Systems, Inc.: Chicago Franchise Systems, Inc. franchises operates Italian-based Chicago-style restaurants in Illinois, Georgia, California and Missouri which specialize in Chicago-style cuisine They have operated since 1990, when they took over the popular Nancy's Pizza chain of pizzerias.  Nancy's itself was started in 1971 by Nancy and Rocco Palese, a couple who claims to have invented the concept of stuffed pizza.  Today, there are 36 Nancy's locations in Chicago metropolitan area, as well as two location in the Atlanta, Georgia area, and one in the Los Angeles, CA area.  CFS, Inc. operates Al's Beef, a popular Italian beef restaurant that is extremely well known in downtown Chicago and is regarded as one of the best beef sandwiches in the country.  CFS, Inc. just launched Doughocracy Pizza + Brews, a fast casual pizza place that gives customers the "Freedom to Choose" their own toppings on a hand stretched pizza crust that can be paired with local craft beers.  There are two Doughocracy restaurants, one in Geneva, Illinois and one in University City, Missouri, a suburb of St. Louis.

Fox Theatres: Fox Theatres was a large chain of movie theaters in the United States dating from the 1920s either built by Fox Film Corporation studio owner William Fox, or subsequently merged in 1929 by Fox with the West Coast Theatres chain, to form the Fox West Coast Theatres chain.  Fox West Coast went into bankruptcy and was sold to The National Theatres Corporation, led by Charles Skouras, on November 20, 1933 for $17,000,000.00.  Eugene V. Klein later became CEO of National, and turned it into the conglomerate National General.  Mann Theatres bought National General's theatres in 1973.

Peter Piper Pizza: Peter Piper Pizza is an Arizona-based pizza chain with locations in Arizona, California, New Mexico, Texas, Oklahoma, Nevada, and Mexico, and formerly in Colorado, Utah, and Michigan.  Restaurants usually have a large dining area that adjoins a game room with playground equipment and classic arcade games.

Supporting paragraphs: Mountain Mike's Pizza Dion's
Answer: Mountain Mike's Pizza