This statistical category is the sum of employed and unemployed persons who are 16 years or older, not full time students, and are actively seeking employment.

The total number of unemployed people is the statistic.

Explanation:

The number of unemployed people is defined by the number of people who do not have a job but are actively seeking employment.

This also has a filter on the total population against the age limit below which it is not legally permissible to work.

So, considering all these filters have been met in the description of the statistic mentioned in the question it is easy to assume that this statistic is about the total number of people who are unemployed in an area or a country.

d. i assume the underlined word is "role." reformat if it isn't.

explanation:

role is closest to part because when replacing words, "playing a vital decision," "playing a vital activity," and "playing a vital dollar" don't make logical sense. the only meaningful choice is "playing a vital part."

this fits one of merriam-webster's definitions of role: "a function or part performed especially in a particular operation or process."