For a cubic spline with one knot, how can we connect the two pieces of the equation to find coefficient estimates?

For a cubic spline with one knot, how can we connect the two pieces of the equation to find coefficient estimates?

• A. Match the second derivatives of each piece
• B. Match the first derivatives of each piece
• C. Match the function values at the knot
• D. Solve for continuity of the third derivative

Answer: (A)