Answer:
The correct answer is - develop new methods to test the hypothesis.
Step-by-step explanation:
Human produce offsprings long time and development also take a long time in general and then to test a hypothesis, regarding the gene therapy helps to treat a disease, would take even more time.
So testing this hypothesis required developing a new method as other options are not possible. You can not change the time it takes in reproduction. Giving up is not the option in science.