Tennis ball, flowers, and some other stuff.
The correct answers are ATMOSPHERE and BIOSPHERE. Nitrogen is most abundant in the ATMOSPHERE, but nitrogen can't be absorbed by the BIOSPHERE without the help of a special bacteria and without undergoing a process called nitrogen fixation.
The post mortem interval of a body enclosed in a plastic bag could be best estimated by the insects found in the body, in that case forensic science need to listen to what those little creatures have to say, insects could tell if the body has been moved from the crime scene, how long it´s been in an specific place, and how long it´s been since death until found, every group of insects can tell something different, from worms, arachnids to flyes, each one of them has a time to get into the body, so it could tell you for how long it´s been dead.
Oceanic Crust is the thinnest