Final answer:
The goodwill message is sincere and enthusiastic, expressing a positive tone and appreciation for the customer's business.
Step-by-step explanation:
The sentences from the goodwill message are best described as sincere and enthusiastic. They express pleasure in welcoming a new customer and look forward to future business, while showing appreciation for a recent large order. The tone is positive, aiming to foster a good relationship with the customer by acknowledging their importance to the company.
The message shows genuine appreciation for the customer, expressing pleasure in welcoming them as a valued customer and excitement for future business. The mention of the size of the recent order further demonstrates the company's appreciation and satisfaction.
Therefore, the correct answer is a. sincere and enthusiastic.