List the three sources of standards.

When processing a stack:

a. Additions are at one end and deletions are at the other end. b. Additions and deletions are both at the same end. c. Additions are at the top and deletions are at the bottom. d. Additions are at the bottom and deletions are at the top.

Each item in a List Box has a(n) ____________, which is an integer that identifies the item’s position in the List Box.

a. index b. list number c. unique identifier d. table key