Take context from the input text and decide on the accurate relationship between 'Baidu' and 'search engine' from the options provided.
Options: product/material produced, subsidiary, headquarters location, founded by

And on the other side, besides Tmall Auto, we have been also cooperating with Baidu Youjia, and that is the auto segment of the Baidu portal, which is the largest search engine in China.
product/material produced