Fraud, fraudulent behaviour and their prevention in business

BNG Co has recently discovered that it has been the victim of a false?billing fraud. Which
of the following controls could BNG put in place to prevent this from occurring in the
future?
A Segregation of duties within the accounts department
B Regular receivables ledger reconciliations
C Authorisation of payments by management
D Maintenance of a regular trial balance

answer: C
but I don’t understand why is C, and why not A, Segregation of duties also prevent this kind of Fraud.