The correct option is
D strong determination and iron will.
It is clearly illustrated in the middle of the passage that - '
A man with determination and iron can defeat all hurdles in the way of his mission.'The author explains that with strong determination, man can achieve anything he sets his mind on, however impossible it may seem.
Therefore Option B is correct.
To achieve success, one needs to work hard in addition to coping with all situations.
Therefore Option A is incorrect.
Merely by becoming strong, one cannot achieve success.
One needs to cope with their circumstances and work hard towards their goal.
Hence Option C is incorrect.
There is no evidence in the passage to suggest that Option D is correct.
Hence Option D is not the right answer.