Answer:
The correct answer is - discovering or diagnosing the disease.
Step-by-step explanation:
According to the question, this technology includes genetically modifying a common virus in order to destroy or kill the deadly brain tumor without affecting normal cells around the tumor, this technique is genetic engineering.
This technique can help in treating or curing the disease by killing the tumor cells and make them non-lethal. It can also prevent the tumor cells to grow and make them controlled. There is nothing mention related to diagnosing the disease in the question and it is not possible to find this tumor with help of such a technique.