Which statements describe gene therapy? Check all that apply. It cures all cases of cystic fibrosis.

It involves the modification of DNA

It is easy to apply to all cells affected by the disorder

It attempts to replace a mutated gene with normal DNA.

It does not always cure patients who use it.

Gene therapy  can be described as an important application of biotechnology that is used to introduce normal genes into the cell, which possess defective or missing gene. It is significant in treating genetic disorders ( for instance, it cures cystic fibrosis by introducing normal gene for CFTR protein). This means that DNA with defective gene is modified or replaced with a normal DNA segment ( gene).

But it does not always cure the patients who use it ( for instance,   inserted gene may be recognized as foreign by immune system of the patient, which destroys the inserted gene).

Thus, the correct answers are-

It cures all cases of cystic fibrosis.

It involves the modification of DNA.

It attempts to replace a mutated gene with normal DNA.

It does not always cure patients who use it.

It seems that you have missed the necessary options for us to answer this question, so I had to look for it. Anyway, here is the answer. A  paleontologist is trying to be study the DNA of a fossil from an extinct animal called x. He has formulated three hypotheses, and the hypothesis that cannot be tested is this: X's DNA consists of a single strand. Hope this helps.