To calculate the labor force of Aridia in 2011, we use the following formula:
\[ \text{Labor Force} = \text{Number of Employed} + \text{Number of Unemployed} \]
From the data given for 2011:
- Number of employed = 1,300
- Number of unemployed = 600
Now, we can calculate the labor force:
\[ \text{Labor Force} = 1,300 + 600 = 1,900 \]
Therefore, the labor force of Aridia in 2011 was 1,900.
The correct answer is: a. 1,900.