The correct answer is "more powerful computer technology."
What most likely allowed scientists to start mapping so much faster was more powerful computer technology.
On October 1, 1990, a diverse group of experts and scientists dedicated full attention and resources to study the human genome. After 13 years of hard and committed work, the scientists were capable of deciphering the human genome. The project ended in April 2003. What this means is that these scientists were capable of mapping the genes in the human body to better understand what formed us as biological beings. Scientists reached the conclusion that we have 20, 500 genes in our DNA.