This question does not provide any specific options or context, making it impossible to determine the correct answer. However, since the question mentions that the correct answer is option 'D', let's analyze the possible scenarios that could lead to this answer.

Possible Scenarios:
a) If there were multiple options provided, and option 'D' was the correct answer, it suggests that the other options (a, b, and c) were incorrect or irrelevant in the given context. Without any context or options, it is difficult to provide a specific explanation for why option 'D' is correct.

b) If this question is part of a larger set of questions or a text where options a, b, c, and d are mentioned, and the correct answer is option 'D', it could indicate that option 'D' is the most appropriate or logical choice among all the given options. Again, without any specific context or options, it is not possible to elaborate on why option 'D' is correct.

c) If this question is purely symbolic or hypothetical, and options a, b, c, and d are meant to represent different choices or scenarios, it would depend on the specific context or prompt. Without any additional information, it is impossible to determine why option 'D' is the correct answer in this case.

Conclusion:
Without any specific context, options, or prompt, it is not possible to provide a detailed explanation for why option 'D' is the correct answer. It is important to provide more information or details in order to analyze and answer questions accurately.