The bones are called clavicle
Human activities that can increase the rate would be air from a car exhaust, large factories, and gas lawn mowers. All of these make rain more acidic which causes more chemical weathering.
Answer: bacteria, fungi, protozoa, worms, viruses, and even infectious proteins called prions.
Isostatic stretching is a flexibility training which is in a advanced form. It should be performed with CAUTION. It is important to avoid isostatic stretches because they can disrupt muscle growth and it fatigue the muscles. Its recommended to do some warm up before doing these stretches honestly.