Analyze the relationship between 'American Girl' and 'doll' within the context of the input sentence.
Options: product/material produced, publisher, original broadcaster, founded by

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.
product/material produced