For each of the following service departments, select the activity base listed that is most appropriate for charging service expenses to responsible units. Your answer should include the number of the activity base only.

Activity bases to choose from:

1. Number of conference attendees
2. Number of computers
3. Number of employees trained
4. Number of cell phone minutes used
5. Number of purchase requisitions
6. Number of sales invoices
7. Number of payroll checks
8. Number of travel claims

Service Department	Activity Base
a. Accounts Receivable
b. Central Purchasing
c. Computer Support
d. Conferences
e. Employee Travel
f. Payroll Accounting
g. Telecommunications
h. Training