The correct answer is: A. would not have got
The hens would not have got into the house if you had shut the door. This is because the door would have been closed, and the hens would not have been able to open it.
The other options are incorrect because they do not accurately reflect the situation. Option B, did not get, is incorrect because it implies that the hens did get into the house, which is not the case. Option C, does not get, is incorrect because it implies that the hens are not able to get into the house, which is also not the case. Option D, not got, is incorrect because it is grammatically incorrect.