A. Review your privacy settings by going to 'Settings' > 'Privacy' on your Facebook account. Adjust your settings to limit who can see your posts, friend requests, and personal information. You can also manage your ad preferences to control how your data is used for advertising.
B. Consider using Facebook's 'Off-Facebook Activity' tool to see what data is being collected from other apps and websites. You can manage this data and even disconnect it from your Facebook account.