阅读下列短文，从每题所给的A、B、C、D四个选项中，选出最佳选项。
D
Failure is probably the most exhausting experience a person ever has. There is nothing more tiring than not succeeding.
We experience this tiredness in two ways: as start-up fatigue(疲惫) and performance fatigue. In the former case, we keep putting off a task because it has either too boring or too difficult. And the longer we delay it, the more tired we feel.
Such start-up fatigue is very real, even if not actually physical, not something in our muscles and bones. The solution is obvious though perhaps not easy to apply: always handle the most difficult job first.
Years ago, I was asked to write 102 essays on the great ideas of some famous authors. Applying my own rule, I determined to write them in alphabetical(按字母顺序), never letting myself leave out a tough idea. And I always started the day’s work with the difficult task of essay-writing. Experience proved that the rule works.
Performance fatigue is more difficult to handle. Though willing to get started, we cannot seem to do the job right. Its difficulties appear so great that, however hard we work, we fail again and again. In such a situation, I work as hard as I can-then let the unconscious take over.
When planning Encyclopaedia Britannica (《大英百科全书》), I had to create a table of contents based on the topics of its articles. Nothing like this had ever been done before, and day after dat I kept coming up with solutions, but none of them worked. My fatigue became almost unbearable.
One day, mentally exhausted, I wrote down all the reasons why this problem could not be solved. I tried to convince myself that the trouble was with the problem itself, not with me. Relived, I sat back in an easy chair and fell asleep.
An hour later, I woke up suddenly with the solution clearly in mind. In the weeks that followed, the solution which had come up in my unconscious mind provided correct at every step. Though I worked as hard as before, I felt no fatigue. Success was now as exciting as failure had been depressing.
Human beings, I believe must try to succeed. Success, then, means never feeling tired.
According to the author, the unconscious mind may help us（）.
A. ignore mental problems
B. get some nice sleep
C. gain complete relief
D. find the right solution