Hi Rohan,
The trick to answering the "what do you do next" questions is twofold:
1. Know what process you are in the project, based on the background information provided in the question.
2. Understand the order of the 49 processes so you know which process comes next.
For example, if the question implies that you are currently sequencing project activities, then the next step would be estimating activity durations.
There are a lot of questions like this on the exam, so knowing how to answer them is very important. Just understand the order of the 49 processes, and you'll be in good shape.