An advertiser wants to show search ads to people searching for running shoes. She wants her ad to show only for searches who use "running" or a close variant, but she wants to allow for broader matching to "shoes". Which keyword will accomplish this?

running shoes

Explanation:since she wants to see people who use running shoes or wants to focus on displaying an an ad with running shoes , these words will give her that specific but broad Information about running shoes.

A key word is the word that is a key to opening up to what you want.bitvtakes you direct to the information that you desire.

+running shoes

Explanation:

Search advertising or search ad is a process of placing online adverts on web pages which show results from search engine queries. With the use of the same search-engine advertising services, ads can also be sited on Web pages and posts alongside other published content, while Keywords are words or phrases that are embedded to match your ads with the terms that internet users are searching for.

going by the above explanation, for her to add a broader matching keyword to the "shoes" keyword, she just need to add a keyword like "running shoes".