It's clear from the passage that …………

In the few days since her new manager had joined the company, Sandra had been feeling more and more upset. During the long years of her working life here and elsewhere, she had never been faced with the problem of working for such an extremely strict man. Last night, the realization of the problem had come to her, and all through the following busy, emotional day she had tried to assess it. Without precisely knowing why, she had come to the conclusion that she must resign. After several failed attempts, she had finally written a satisfactory letter outlining her reasons for the decision and left it on the boss's desk.