Answer:(b) Only two
(b) Only two
Statement 1 is correct as gold mining activity is indeed a significant source of mercury pollution in the world.
Statement 2 is correct as coal-based thermal power plants can also contribute to mercury pollution due to the release of mercury during the combustion of coal.
Statement 3 is incorrect. While high levels of mercury exposure can be harmful, there are established safe levels of exposure to mercury for various scenarios. The concept of "no known safe level of exposure" is not accurate.
Therefore, two of the statements are correct: Statement 1 and Statement 2.