Answer:
C. The Holy Spirit
Explanation:
In Romans 8:26 we are told that we do not know how to say our prayers correctly. That's because we don't know how to ask for what we want in the way that suits us, with sufficient respect and humility. This is a human weakness that is fixed by the presence of the holy spirit, which is one of the aspects of God, who understands the spirit of our spirit and when hearing our prayers intercede for us in the appropriate way.