Final answer:
The ending balance in the service revenue account would be $14,000, as this is the amount billed for design services and not affected by the subsequent cash collection on account.
Step-by-step explanation:
The ending balance in the service revenue account would be affected only by transactions related to service revenue. In this case, the only transaction affecting service revenue is the billing of a client for $14,000 of design services completed on March 5. The cash received on March 6 is a collection on account for the services previously billed and does not affect the service revenue account.
Therefore, the ending balance in the service revenue account would remain $14,000.