Answer: Convergent plate boundary
Explanation: Convergent plate boundary is a location on earth where two tectonic plates are moving towards each other and the denser plate slides beneath the less dense plate (this process is known as subduction). The collision of these plates results in earthquakes, volcanoes, and formation of mountains.
There are three types of convergent plate boundary
1. Oceanic- Continental Convergence
2. Continental- Continental Convergence
3. Oceanic- Oceanic Convergence
In the case, of Papua New Guinea, it was formed by the collision of the very large northward moving Indo-Australian tectonic plate with the even large westward moving Pacific plate.