It cannot be concluded that many old day economists who dealt with real world data ended up:
Tackling modest questions.
In the paragraph that talks about the economists in the ‘80s, consider the line, “Many economists concluded that the path to knowledge lay in solid answers to modest questions. This is pertaining to the ‘80s economists and hence tackling modest questions cannot be attributed to old day economists. All the other options are in the context of old day economists. This can be seen from the lines “For more than a generation after the Second World War, the economists who dealt with real world data were mostly earnest, stubborn men. They tackled the era’s thorniest questions. Zvi Griliches of Harvard devoted decades to the problem of productivity growth, the chief determinant of rising living standards. His colleague Simon Kuznets spent half his career devising the measure of economic growth we still use today.” Hence option (d) is the correct answer.