Explanation:

Marketing Cloud is designed for managing multi-channel marketing campaigns, including social media platforms like Facebook, Twitter, and Instagram.

It enables tracking of online engagement, audience interactions, and campaign performance across these channels, which fits well for an event like an annual Giving Day.

Marketing Cloud’s Social Studio feature specifically allows managing and measuring social media engagement in one place.

Why not the others?
A. Campaign Influence tracks how campaigns influence sales or donations but doesn’t provide direct multi-channel social media engagement tracking.
B. Salesforce Inbox is focused on email and calendar productivity for sales reps, not social media or campaign tracking.