a hard-tissue sarcoma usually involving the upper shaft of the long bones is called a

A hard tissue sarcoma usually involving  the upper shaft of the long bones is called the osteosarcoma. This is a type of cancer that starts in the bones, the cancer cells in these type of tumor appear like early forms of bone cells that help make a new bone tissue.The first sign are the pain and swelling, pain in the affected bone is most common symptom of osteosarcoma, which often increases with activity and might result in a limp if the tumor is in a leg bone. 

The best answer is C - DNA is heated to separate the strands. PCR proceeds in three steps. 1. Denaturation - The DNA strands, which are bound together in the double helix, must be separated to allow replication to take place so the first step of PCR is to separate them. This is done by heating up the sample, breaking the hydrogen bonds between the strands. 2. Annealing - sample is cooled just enough to allow primers to bind to the ends of each of the two template strands. 3. Extension - DNA polymerase attaches to the primers and makes a copy of each template strand.