Final answer:
The most effective strategy to prevent ads from showing too broadly is to implement negative keywords, which helps refine your target audience and ensures your ads are not displayed to irrelevant viewers.
Step-by-step explanation:
When managing ad spend to prevent your ads from showing too broadly, the most effective strategies are to set specific targeting options and use keyword matching options wisely. The option that directly helps to avoid showing ads too broadly is c) Implement negative keywords. By specifying negative keywords, you can exclude search terms that are not relevant to the products or services you are advertising, thus refining your audience and preventing your ads from being shown to an overly broad audience. Setting a high daily budget (a) could lead to overspending, using broad match keywords (b) will likely increase the ad's reach (but also its breadth), and targeting a global audience (d) would expand the potential reach without ensuring the relevance of that audience.