OFFICIAL EXPLANATION
In the process of developing a successful career, self-motivation's importance is paramount.
(A) In the process of developing a successful career, self-motivation's importance is paramount
This answer choice is grammatically incorrect: self-motivation is an abstract noun, and using 's to express possession is only allowed with concrete nouns.(B) When developing a successful career's process, the importance of self-motivation is paramount
Incorrect.
While this answer choice corrects the original Possession mistake, it is still grammatically incorrect: career is an abstract noun, and using 's to express possession is only allowed with concrete nouns.
Also, this answer choice changes the meaning of the original sentence by linking the word process to career. In the original sentence, what is developed is a career. In this answer choice, what is developed is a process.(C) The importance of self-motivation is paramount in the process of developing a career filled with successes
Incorrect.
Although this answer corrects the original Possession mistake and is grammatically correct, it is stylistically flawed. Replacing the two-word phrase successful career with the four-word phrase career filled with successes creates redundancy. This phrase is not only wordy but also awkward.(D) Self-motivation's importance is paramount when in the process of developing a successful career
Incorrect.
This answer choice is grammatically incorrect and repeats the original mistake: self-motivation is an abstract noun, and using 's to express possession is only allowed with concrete nouns.
This answer choice is also stylistically flawed as the addition of the word when creates redundancy.(E) The importance of self-motivation is paramount in the process of developing a successful career
Self-motivation is an abstract noun, so the correct way to express possession to it is using of rather than 's.