Which of the following is not correct? Select one: O a. The methods for storing files of data in secondary storage are sequential file organization, direct file organization, and indexed file organization O b. A CD-ROM may not be written to by a PC O c. Data stored in a batch processing mode is always up-to-date O d. The time needed to access data on a disk drive is the sum of the seek time, the head switch time, the rotational delay, and the data transfer time