Utilize the input text as a context reference, choose the right relationship between American Girl and doll from the options. Options: product/material produced, manufacturer, distributed by, industry, position held, original broadcaster, owned by, founded by, distribution format, headquarters location, stock exchange, currency, parent organization, chief executive officer, director/manager, owner of, operator, member of, employer, chairperson, platform, subsidiary, legal form, publisher, developer, brand, business division, location of formation, creator.

Mattel's portfolio of best-selling brands includes Barbie ® , the most popular fashion doll ever produced, Hot Wheels ® , Monster High ® , American Girl ® , Thomas & Friends ® and Fisher-Price ® brands, including Little People ® and Power Wheels ® , MEGA ® Brands, including MEGA BLOKS ® and RoseArt ® , as well as a wide array of entertainment-inspired toy lines.

Answer: product_or_material_produced