The correct answer is option 1 - 1 only.

Statement 1 is correct. NEOSSat is indeed the only space telescope dedicated to searching for asteroids that could pose a threat to Earth. Its name stands for "Near-Earth Object Surveillance Satellite," highlighting its primary mission of detecting and tracking Near-Earth Objects (NEOs).

Statement 2 is incorrect. NEOSSat was not designed and developed by ISRO (Indian Space Research Organisation). It was a collaborative effort between Canada and Defence Research and Development Canada (DRDC). The satellite`s payload, the Near-Earth Object Surveillance Satellite Space Telescope (NEOSSat SST), was developed by DRDC, and the spacecraft platform was built by the Canadian Space Agency (CSA).

In summary, NEOSSat is the only space telescope dedicated to searching for potentially hazardous asteroids near Earth. However, it was not designed and developed by ISRO, but rather by Canadian organizations DRDC and CSA.