An advertiser is testing Pinterest and wants to understand the impact Pinterest has on its conversions across multiple channels. The advertiser has run conversion/shopping campaigns for the past three months and wants to learn more about conversions from these campaigns compared to what it sees as its source of truth. Which measurement solution should the advertiser use?

Multi-touch attribution (MTA) is the correct solution because it assigns credit to all touchpoints a customer encounters before converting, providing a holistic view of Pinterest's impact alongside other channels. The advertiser wants to understand Pinterest's contribution relative to their "source of truth," which implies comparing data across different platforms. Pinterest conversion analysis would only show conversions attributed to Pinterest, not the cross-channel impact. A 3P foot traffic study is irrelevant as the advertiser is focused on online conversions, not in-store visits. A Pinterest 6Q brand lift study measures brand metrics like awareness or recall, not conversion impact.