Dynamic Programming

Define $R_n$ to be the maximum amount earned by cutting a rod of length $n$ meters into one or more pieces of integer length and selling them. For $i > 0$, let p[i] denote the selling price of a rod whose length is i meters. Consider the array of prices: p[1] = 1, p[2] = 5, p[3] = 8, p[4] = 9, p[5] = 10, p[6] = 17, p[7] = 18 Which of the following statements is/are correct about $R_7$?