Final answer:
The number one predictor of successful counseling is client motivation. So, the correct answer is option c.
Step-by-step explanation:
The number one predictor of successful counseling is client motivation. While all the other options (communication skills, empathy, and therapist experience) are important factors in counseling, client motivation is the most strongly predictive factor of success. A motivated client is more likely to actively engage in the counseling process and make progress towards their goals.
So, the correct answer is option c.