Question

the kola superdeep borehole was stopped after drilling down ____ km because of melted rock. 38 2 12 145

Explanation:

The Kola Superdeep Borehole is a well - known scientific drilling project. It reached a depth of about 12 km before being stopped due to issues like melted rock. 38 km and 145 km are much deeper than what was actually achieved. 2 km is too shallow compared to the known depth of this significant borehole.

Answer:

12