In Java, how can the readNumbers method be updated to quit only when a 'q' is entered and to reject all other non-integers with the error message: "Not an integer"?
a) Implement a try-catch block to catch NumberFormatException and print "Not an integer" message.
b) Use a Scanner object to read input and check if it's an integer before proceeding.
c) Modify the while loop condition to check for 'q' input and break the loop accordingly.
d) Use a regex pattern to validate input and handle non-integer cases appropriately.