A (n) _______________ is an injection of weakened or dead viruses or bacteria, or pieces of proteins from weakened or dead virus
es or bacteria. It is given to help the immune system of people "learn" how to defeat the real virus or bacteria. A) antibiotic B) antibody C) pathogen D) vaccine
An embolus <span>occurs when a clot breaks free from an artery wall and travels through the circulatory system until it lodges in a small artery and suddenly shuts off blood flow to the tissues.</span>
