Write the next sentence in the following story.

How to deal with neurofibromatosis
Know the types.
Neurofibromatosis 1 (nf1), neurofibromatosis 2 (nf2) and schwannomatosis.
Nf1 usually appears in childhood.

[A]. It is a rapid and almost permanent tick-down. It is the least treatable form of neurofibromatosis.;
[B]. Malignant neurofibromatosis is a family encephalitis in which infants are exposed to a virus, bacteria and fungus. The cells in this virus are compressed and then die down and become increasingly more susceptible to infection.;
[C]. Most commonly, neurofibromatosis often appears after surgery or radiation at age 18. It can appear of its own in babies as young as two years, but in older adults it can appear more often during a few years.;
[D]. Signs are often present at birth or shortly afterward, and almost always by the age of 10. Signs and symptoms are often mild to moderate, but may also vary in severity.;. The answer should be
[D].