Answer:
C. She can require the witnesses to testify.
Explanation:
The Sixth Amendment was created to guarantee the rights of criminal defendants so that all criminal prosecutions are carried fairly. And under the amendment, one of the rights that the women has is to have compulsory process for obtaining witnesses in her favor and to request a witness to appear in court. So, "her friend" who witnessed the crime has the duty to testify in the court case.