14. User productivity systems ____.
a. provide job-related information to users at all levels of a company
b. simulate human reasoning by combining a knowledge base and inference rules that determine how the knowledge is applied
c. process data generated by day-to-day business operations
d. include e-mail, voice mail, fax, video and Web conferencing, word processing, automated calendars, database management, spreadsheets, desktop publishing, presentation graphics, company intranets, and integrated mobile computing systems