Given a math problem with context and a question and 5 answer choices, the task is to provide the correct answer choice based on the problem. You must choose one of the given answer choices by letter: a, b, c, d, or e; anything else is invalid.

Problem: a girl scout was selling boxes of cookies. in a month, she sold both boxes of chocolate chip cookies ( $ 1.25 each ) and boxes of plain cookies ( $ 0.75 each ). altogether, she sold 1,585 boxes for a combined value of $ 1, 588.25. how many boxes of plain cookies did she sell ?
Options: a. 0, b. 233, c. 500, d. 695, e. 786
e