Horace Mann is best known for his contributions to the public education system in the United States, particularly through his advocacy for funding and improving educational standards. The correct answer regarding his contributions to the reform in education is:
C. His pressure on the state legislature provided money to fund new schools and increase teachers' pay.
Mann was a strong advocate for public education, and he worked to establish a system of public schools that would be funded by the state, ensuring that education was accessible to all children regardless of their background. His efforts were instrumental in establishing the principles of universal public education.