What is any factor that makes it difficult for a new firm to enter a market referred to as

Barriers of trade

Explanation:

Barriers of trade refers are obstacles that make it difficult for new business competitors to enter an industry. It is an economic term that describes restrictive conditions to entry in a particular sector.   Existing firms benefit from barriers to trade as their revenues and profits are protected.

Barriers to trade may be as a result of high start-up cost, natural reasons, or government policy.  High start-up is the capital required is high that discourages new entrants. Natural reasons may include the presence of resources such as high-value minerals in specific geographical areas. Barriers to trade make the market less competitive.

answer: a. the kind of population living in your neighbourhood.

the census explorer data tool by the us census bureau allows the user to zoom in on any neighbourhood within the united states and find the kind of people residing in that by race and age.  

the tool needs to needs to be used twice – once in order to find what type of people reside in a neighbourhood, and then to see the age groups of the people in the same neighbourhood.