Which of the following information, gathered in an analysis of the general environment, would indicate an opportunity for an entrepreneur who wishes to open a business providing "Fitness for Life" physica conditioning services $($strength$,$ balance, and flexibility training$)$ in a city of $100,000$ people?

a$.$ The average education level of the population in his community is low.

b$.$ The level of unemployment in his community is high.

c$.$ The average age of the population in his community is high.

d$.$ A chiropractor and two independent physical therapists are located in his community.