Cost units and inventories

QUESTION 1
which of the following items might be a suitable cost unit within the credit control department of a company?
(1) stationery cost
(2) customer account
(3) cheque received and processed

A item 1 only
B item 2 only
C item 3 only
D item 2 and 3 only

QUESTION 2
Which of the following is correct with regard to inventories
(1) stock outs arise when too little inventory is held
(2) safety inventories are the level of units maintained in case there is unexpected demand
(3) a re-order level can be established by looking at the maximum usage and the maximum lead time

A (1) and (2) only
B (1) and (3) only
C (2) and (3) only
D (1) , (2) and (3)