Answer :
Final answer:
The remaining population not working in Italy, after subtracting the part-time and full-time workers from the total civilian noninstitutionalized working-age population, is 18.31 million people.
Explanation:
To calculate the remaining population of the civilian noninstitutionalized working-age population in Italy, given that there are 4.4 million people working part-time and 13.19 million working full-time, we can subtract the sum of part-time and full-time workers from the total population. The total working-age population is 35.9 million. Therefore, the remaining population is:
35.9 million (total population) - 4.4 million (part-time workers) - 13.19 million (full-time workers) = 18.31 million.
This means that the remaining population, or those not working, amounts to 18.31 million people, which corresponds to answer option (a).