Based on the search results, Donyi Polo Airport and Kushinagar International Airport are confirmed as Greenfield projects. Donyi Polo Airport in Itanagar is explicitly mentioned as a Greenfield airport. Similarly, Kushinagar International Airport is listed among India's Greenfield airport projects. However, there is no confirmation that Vijayawada International Airport is a Greenfield project. Therefore, the correct option is 1: 1 and 2 only.