The correct answer is - A) Permafrost used to be permanent.
The permafrost used to be permanent until recently, so using certain techniques of building on it functioned properly. But with the climate changes that are becoming more and more evident, the permafrost is no longer permanent, but instead, it is either defrosting in some part of year and then forming again, or has been totally absent from some regions in the present.
That has caused changes in the rules governing building on permafrost. The reason for the changes is that the old techniques do not work properly anymore, and the permafrost changes are making change in the landscape, making big damages on the infrastructure in meantime.
You could only budget a car for five days....Hope this helps.
The times of moonrise and moonset are based on ideal situations. The time of moonrise is calculated based on the fact, when the top part of the moon is above the horizon. The moonset time is considered as the time when the moon is just about to go below the horizon. I hope the answer helps you.
