can you help with answer for below, i believe (b) is correct answer, any views?

During planning processes, you used Monte Carlo simulation to quantitatively assess cost and schedule risks of your project. During risk control, you repeat the technique, and it leads to different results. What should not be the reason for that?

o Some assumptions during planning have meanwhile become fact-based knowledge, so that the risks related to them have vanished or have become certain problems.
o New risks may have been identified.