OG 12-10(otherwise 已解决)

10. Carnivorous mammals can endure what would
otherwise be lethal levels of body heat because they
have a heat-exchange network which kept the brain
from getting too hot.
(A) which kept
(B) that keeps
(C) which has kept
(D) that has been keeping
(E) having kept

句子中的otherwise, 不理解为啥GMAC这么用，望NN们解答

查了longman字典如下，没有可以对号入座的解释

oth?er?wise S1 W2
1 [sentence adverb] used when saying what bad thing will happen if something is not done:
You'll have to go now, otherwise you'll miss your bus.
Put your coat on, otherwise you'll get cold.
2 [sentence adverb] used when saying what would have happened or might have happened if something else had not happened:
We were delayed at the airport. Otherwise we would have been here by lunch time.
They got two free tickets to Canada, otherwise they'd never have been able to afford to go.
3say/think/decide etc otherwiseto say, think, or decide something different:
The government claims that the economy is improving, but this survey suggests otherwise.
A lot of people think otherwise.
4 except for what has just been mentioned:
He was tired but otherwise in good health.
[sentence adverb]
I could hear the distant noise of traffic. Otherwise all was still.
[+ adjective/adverb]
This spoiled an otherwise excellent piece of work.
Their arrival livened up an otherwise dull afternoon.
5or otherwiseespecially British English used to refer to the opposite of what has just been mentioned:
We welcome any comments from viewers, favourable or otherwise.
The truth or otherwise of this diagnosis would be revealed in the future.
6otherwise engagedformal busy doing something else:
I'm afraid I will be otherwise engaged that day.
7otherwise known asalso called:
Albert DeSalvo, otherwise known as the Boston Strangler
8 formal in a different way:
people who smoke or otherwise abuse their bodies
9it cannot be otherwise/how can it be otherwise?formal used to say that it is impossible for something to be different from the way it is:
Life in the military is hard - how can it be otherwise?