Ben collects and sells stamps. He starts with x3 stamps, for some number x, and then buys 7x5, and trades for another x2. He then sells 7x, and finally sells another 19 stamps. Write an expression for the number of stamps Ben now has in standard form. A. −19 + 7x5 − 7x + x3 + x2 B. x3 − 7x + 7x5 − 19 + x2 C. 7x5 + x3 + x2 − 7x − 19 D. −19 − 7x + x2 + x3 + 7x5