Who told Pharaoh about Joseph's ability to interpret dreams?

In Genesis 41:9-13, when Pharaoh was troubled by dreams that none of his magicians or wise men could interpret, the cupbearer (chief butler) finally remembered Joseph. He told Pharaoh: "I remember my faults today. When Pharaoh was angry with his servants and put me and the chief baker in custody... a young Hebrew was there with us, a servant of the captain of the guard. When we told him our dreams, he interpreted them to us... and things turned out exactly as he interpreted."

This testimony prompted Pharaoh to summon Joseph from prison. Joseph then successfully interpreted Pharaoh's dreams about the seven years of abundance followed by seven years of famine, which led to his appointment as second-in-command over all Egypt.

The cupbearer is the correct answer because he was the direct link between Joseph and Pharaoh. Potiphar was Joseph's earlier master who had him imprisoned. Pharaoh's wife is not mentioned in this context. The magicians of Egypt had already failed to interpret the dreams and had no knowledge of Joseph's ability.