Given the task definition and input, reply with output. 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: the average monthly salary of 8 workers and one supervisor in a factory was 430. @ sswhen @ ssthe @ sssupervisor @ cc @ sswhose @ sssalary @ sswas @ ss 430. @ sswhen @ ssthe @ sssupervisor @ cc @ sswhose @ sssalary @ sswas @ ss 430. whenthesupervisor, whosesalarywas 430. when the supervisor, whose salary was 870 per month, retired, a new person was appointed and then the average salary of 9 people was $ $ 440 per month. the salary of the new supervisor is :
Options: a. 233, b. 960, c. 287, d. 771, e. 191
b