Which Semrush tool helps a PPC specialist create and maintain a comprehensive list of keywords for future PPC campaigns?

Keyword Manager is the correct answer because it is specifically designed for PPC specialists to create, organize, and maintain comprehensive lists of keywords. It allows users to import keywords, add new ones, group them, and export them for use in campaigns. PLA Research (Product Listing Ads) focuses on competitor product ads, not general keyword list creation. Position Tracking monitors keyword rankings for a website, which is a post-campaign analysis tool, not a pre-campaign keyword list builder. Organic Research analyzes a competitor's organic keyword profile, which can inform keyword strategy but isn't the primary tool for building and managing your own comprehensive PPC keyword lists.