Paper 1 October/November 2011 Accounting (9706/11) A Level

Why does a business maintain sales and purchases ledger control accounts as part of the double entry accounting system?
1 It allows a trial balance to be prepared easily from the nominal ledger.
2 It can involve separate employees which makes fraud more difficult.
3 There is no need to keep sales and purchases journals.
4 There is no need to reconcile with personal accounts for customers and suppliers.