Cost and schedule performance indexes should be as close to 1 as possible. A larger value, such as 2.12, means that the schedule duration estimates were likely bloated or incorrect to begin with.

Answer option B is incorrect. This is not the best choice for this question.

Answer option C is incorrect. The number should not be close to 100; it should be close to 1.

Answer option D is incorrect. While Mark may have crashed the schedule and driven up costs to achieve the SPI value, a more likely reason is that the time estimates were bloated.