Which best exemplifies the use of social media to save lives in a fast$-$moving disaster event?

A$.$ Using YouTube to post videos from the County Executive at a ceremony honoring disaster survivors

B$.$ Posting pictures of property damage to Flickr after a tornado

C$.$ Updating a blog with the locations of application centers for disaster assistance loans

D$.$ Tweeting warnings of road closures and hazardous conditions during a snowstorm