Officer Jones explains that the owner of the diner does not charge police officers, which is why he chose that particular diner. This is an illustration of:

Gratuity    

Explanation:

Officer Jones explains that the owner of the diner does not charge police officers, which is why he chose that particular diner. This is an illustration of gratuity.

Gratuity in this context refers to something given freely/voluntarily to someone else for service. The diner gives free meals to the police officers for their job in protecting the city or the area where the dinner is located.

the first part is ocean

explanation:

the factors that the economies of the muslim empires prosper were:

1- land trade routes-located between three continents  

2- sea trade routes

trade contributed to the spread of muslim empires, and with that islamic culture led to a growing feeling of internationalism resulted in the transfer of technology, science, and other cultural forms.