Answer:
genetic engineering
Step-by-step explanation:
Genetic modification or Genetic engineering is the method of using recombinant DNA (rDNA) technology to change an organism's genetic makeup.
In Genetic egineering a gene is isolated from the body of one organism and incorporated into the body of host cell in order to produce new gene variety with some advantages.
Here also, scientists have incorparetd a barley gene into a type of rice that developed a new rice variety with muchlower methane emissions.
Hence, the process used by scientists is genetic engineering.