Industrial exhibitions play a major role in a country's economy. Such exhibitions, now regularly held in Delhi, enable us to measure the extent of our own less advanced industrial progress and the mighty industrial power and progress of countries like the U.K., U.S.A. and Russia whose pavilions are the centres of the greatest attention and attractions.

The passage best supports the statement that industrial exhibitions -

The passage discusses the role of industrial exhibitions in measuring the industrial progress of a country and compares the progress of less advanced countries with the industrial power of countries like the U.K., U.S.A., and Russia. Here's the analysis of the options based on the passage:

1. Option A - greatly tax the poor economies:
   • The passage does not discuss the economic burden of industrial exhibitions on poor economies. Instead, it focuses on their role in measuring industrial progress and comparing it to more advanced countries.
   • This option is not supported by the passage.
2. Option B - are more useful for the developed countries like U.S.A. whose products stand out superior to those of the developing countries:
   • The passage does mention that the pavilions of the U.K., U.S.A., and Russia are centers of greatest attention, implying that their products are more advanced and attract more attention. However, it does not directly state that industrial exhibitions are more useful for developed countries.
   • This option is partially supported, but it overemphasizes the benefit to developed countries at the expense of developing countries.
3. Option C - are not of much use to the countries who are industrially backward:
   • The passage does not suggest that industrial exhibitions are not useful for industrially backward countries. It discusses how such exhibitions enable these countries to measure their industrial progress and compare it with more advanced nations.
   • This option is not supported by the passage.
4. Option D - boost up production qualitatively and quantitatively by analytical comparison of a country's products with those of the developed countries:
   • The passage mentions that industrial exhibitions allow us to measure our own industrial progress in comparison with the industrial power of countries like the U.K., U.S.A., and Russia. This suggests that such exhibitions help in analyzing and comparing products, which could lead to improvements in production qualitatively and quantitatively.
   • This option is strongly supported by the passage.
5. Final Answer:
   • The best supported statement by the passage is D. boost up production qualitatively and quantitatively by analytical comparison of a country's products with those of the developed countries.