Which of these choices would make a good secondary bid strategy for a client who wanted to run on Smart Shopping campaigns and use Maximize Conversion Value as a bid strategy?

Target Return On Ad Spend (tROAS) is the most suitable secondary bid strategy for Smart Shopping campaigns aiming to maximize conversion value. Smart Shopping campaigns are designed to optimize for conversion value, and tROAS directly aligns with this goal by allowing you to specify a desired return for your ad spend. This helps the system prioritize conversions that generate higher revenue. Maximize Clicks focuses on getting the most clicks, not necessarily the most valuable conversions. Enhanced CPC (ECPC) and Manual Max CPC are manual bidding strategies that offer less automation and optimization for conversion value compared to tROAS, which leverages machine learning to achieve your ROAS target.