Third. You only have to look at the photos from that day to realize that whatever hit the Pentagon did not bounce off the lawn.
Who said anything "bounced off" the lawn?
If Flight 77 had crash landed and skidded into the Pentagon, it would have looked like this.
"Crash landed and skidded?" What in the world are you talking about?
Instead, it looked like this, without a single scratch on the lawn.
http://www.loosechangeguide.com/images/image039.jpg
This stuff would be hilarious if the subject wasn't so serious.
If flight 77 had crashed like this, it would have slid across several lanes of highway that was filled with bumper-to-bumper traffic.
Funny, none of the dozens of witnesses reported that happening.