You can add a ‘+’ modifier in front of broad match keywords to…

You can add a ‘+’ modifier in front of broad match keywords to…

  • Overrides negative keywords with an explicit positive keyword.
  • Only trigger ads when the Google+ social extension is available.
  • Indicate that this keyword should be dynamically inserted into your ad text.
  • Specify that certain words must be included in someone’s search term to trigger your ads.

Correct Answer is:

  • Specify that certain words must be included in someone’s search term to trigger your ads.

Explanation: By adding a modifier, your ads can only show when someone’s search contains those modified terms, or close variations of the modified terms, in any order. The modifier won’t work with phrase match or exact match keywords.

Unlike broad match keywords, modified broad match keywords won’t show your ad for synonyms or related searches. For this reason, it adds an additional level of control. Using broad match modifier is a good choice if you want to increase relevancy even if it means you might get less ad traffic than broad match.

You can read more here:
https://support.google.com/partners/answer/2497836?hl=en