Mandy's readiness to be tested conceals how she feels about learning her genetic status. Hence, referring her to a genetic counselor or adolescent psychologist (option C) is preferable, and beginning the process of genetic testing (option B) should be delayed. An opportunity to discuss her thoughts and feelings about her genetic status is important because it's unknown whether she has explored the topic with her parents, or anyone else.
Although discussion with an adolescent psychologist may indicate the need to inform Mandy's parents of her desire for a genetic test, there is no clear evidence that this is necessary. Accordingly, option A (informing Mandy's parents) should also be avoided.
Preferable: Option C
Avoid: Options A and B