Explanation:

Here’s the thing—let’s break down the options for that famous phrase:

- Option 1: David Ricardo – He’s big on comparative advantage and international trade, but he never used the phrase “From each according to his ability, to each according to his needs.”

- Option 2: John Stuart Mill – Known for utilitarianism and welfare economics. Again, not the source of this quote.

- Option 3: Adam Smith – The Wealth of Nations guy. Focused on self-interest and the invisible hand, not this ideal.

- Option 4: Karl Marx – This is the right answer. Marx used that line to sum up his vision for a post-capitalist society—where people contribute what they can and receive what they need.