The green earth, a landscaping company, finds that the most difficult firms to get business from are the because this group considers numerous and even unfamiliar suppliers, solicits bids, and carefully analyzes options; therefore, it requires a higher levels of customer service.

Optimizer

Explanation:

From the following scenario, we can state that Green Earth finds optimizer to be the most difficult firms to get business from. Optimizer are known to be or referred to as an individual or an organization in a very large business market whose tend to perform the task to maximize the profits and thus make their business much more efficient .