According to the text, what is the object of study of Economics?

I - The economic life or economic activities of man.
II - How society responds to the three fundamental questions of any economic system: what to produce and in what quantities, how to produce, and for whom to produce.
III - The laws of production, distribution, and consumption of goods and services that satisfy needs.
a) Only I is correct.
b) Only II is correct.
c) Only III is correct.
d) I, II, and III are correct.