Final answer:
The correct journal entry for Sky Co. collecting $600 from a customer for payment on account would be Debit Accounts Receivable $600; Credit Cash $600.
Step-by-step explanation:
The correct journal entry for Sky Co. collecting $600 from a customer for payment on account would be:
a) Debit Accounts Receivable $600; Credit Cash $600
This entry acknowledges the increase in the Accounts Receivable account and the decrease in the Cash account, as the customer's payment is received.