Answer: d. Extracellular matrix was discovered more than 20 years ago.
Explanation:
According to biological sciences, the extracellular matrix is a matrix that consists of three dimensional network of extracellular macromolecules such as enzymes, collagen and glycoproteins which provide structural and biological support for surrounding cells as well.
It is found that it is discovered over 20 years ago in the matrix formed in the mouse EHS sarcoma. Therefore, correct answer is (d).
RFLP or Restriction Fragment Length Polymorphism exploits the variation of homologous DNA (Deoxyribonucleic Acid) sequences. This technique is frequently used in different types of analysis such as genotyping, paternity tests, forensics, hereditary disease diagnostics, and many others. In diagnosing diseases, PCR is use to find the DNA of pathogens in small amounts to diagnose hundreds of genetic diseases. While in forensic investigations, PCR can give a probably ID from 20 cells.