Let's evaluate each statement:
- Statement (i) is correct as minerals have been used since ancient times for making tools and weapons.
- Statement (ii) is incorrect because not all developed countries are extracting more minerals; some have transitioned to more sustainable sources of energy and materials.
- Statement (iii) is correct since the significant development of mining began during the industrial revolution, which saw large-scale extraction and technological advancements in mining processes.
- Statement (iv) is correct, as the discovery of minerals involves many stages, including exploration, testing, and evaluation.
Thus, the correct answer is (C) Only i, iii and iv are correct.