Bloodstain pattern analysts sometimes are called to gruesome scenes to gather crucial evidence regarding violent crimes. At other times, they might deal only with a single drop of blood or fingerprint.
Answer:
Option D
Explanation:
Bits of DNA that are interspersed among these repeated sequences are called spacers. Regarding to bacteria, the spacers are taken from viruses that previously attacked the organism. They serve as a bank of memories, which enables bacteria to recognize the viruses and fight against future attacks.