Answer:
D. increase the number of employees and increase inventory
Step-by-step explanation:
In order to increase sustainability for the next holiday season, it would be important to increase employees so that the workers would not be exhausted. Also, they have to increase inventory to have inputs needed to produce outputs needed for sustainability.
If customers are increased and employees are decreased, it would further increase the pressure on workers. Also, the inventory might be inadequate to cater for the needs of customers