I believe it is D because the allies weren't formed yet before war broke out but when it did, that's when the allies were formed.
B - Down. Just try and see if it makes sense to be in the sentence
The sentence here contains a participle that is correctly punctuated. We have the phrase hiding in the brush which is our participle, and it clearly defines what the leopard was doing. Its is properly punctuated as the comma was necessary before the words, the leopard or else it would become improperly punctuated.
