D). Too many plans in life prevent people from being happy and fulfilled.
Explanation:
The key idea which the author conveys through the given story is that 'having too many plans in life abstains people from being happy and fulfilled.' The author says that t<em>he excess pressure that we put on ourselves by making such grand plans not only creates unwanted obstacles and problems which we never expect but also ruins individual happiness</em>. This idea is supported through the description of 'rejections and obstacles' that the speaker faced in his huge 10-year plan' which led him to suffer a 'gross understate.' This suggests that <u>we make huge plans without considering the uncertainties and challenges that will come our way and it eventually mars one from their happiness</u>. Thus, <u>option D</u> is the correct answer.
