Dystrophin is a protein that normally

Dystrophin is a protein that normally
  A. shortens and lengthens to produce muscle contraction.
  B. carries signals into muscle cells to initiate contraction.
  C. strengthens the attachment between muscle proteins and the plasma membrane.
  D. helps provide energy for muscle contraction.
  E. signals muscle cells to divide.

Question 2

Which one of the following is NOT usually a symptom of cystic fibrosis?
  A. Low fertility or infertility
  B. Frequent respiratory infections
  C. Difficulty breathing
  D. Loss of pancreatic function
  E. Problems with hearing and vision