Answer:
C. They contain genes transferred from another organism.
Step-by-step explanation:
Genetic engineering or modification is the manipulation of an organism's genome in order to improve it. It is done to bring about the expression of a desired trait in a particular species of organism. Genetic engineering employs the use of recombinant DNA technology i.e. the introduction of a foreign DNA (gene) into an organism's genome.
The inserted gene enables the genetically modified organism (GMO) to exhibit the desired trait. For example, the insulin gene that codes for the insulin protein was inserted through a bacterial DNA into insulin-deficient humans. Based on this, one way or another, genetically modified organisms always contain genes from another organism.