Explain the main characteristics of Facebook ads; illustrate with a "carousel" card ad. Also, identify the main characteristics of Twitter ads, illustrating with a promoted tweet. Finally, list the main characteristics of LinkedIn, showing a sponsored ad. Answers should be based on these articles, which can be found on google: a) "The 5 Most Effective Types of Facebook Ads - And How to Use Them For Your Business"; b) "How to Use Twitter Ads - The Complete Guide for Marketers"; and c) "How to Use LinkedIn Ads to Grow Your Business: The Complete Guide for Marketers".