Sorry, but none of these is right. And I'm not sure that guy you spoke with is a McK Partner if that's what he advocated for.
I'm always fascinated how candidates want to interpret an exhibit on the fly, when as a consultant I've been in a room with senior Partners with 20y of experience and they also went silent for a half a minute to just take in the exhibit. Nobody expects you to be a robot - it's ok to take time to think. Especially when you have little to no experience.
So how should you do it instead?
1. Read the exhibit with the interviewer. Read it, not interpret it. Use this as a chance to get a grasp of what the exhibit stands for, what are the types of data it contains and ask any clarifying questions you might have.
2. Take time. Not a lot. Somewhere between 20-60 seconds is fine. It's always better to take more time than have a shallow, non-insightful answer.
3. Get back to the interviewer with a structured answer. Focus ideally on at least 3 insights. For each of these insights, pick on a data point, explain what it means and then explain what the client should do as a consequence of this findings (this is what actually makes it an insight).
4. For a distinctive interpretation, after you went through these insights, take a step back and try to paint the story for the client of how your refined hypothesis looks like now that you have all this additional data.
I run focused session with candidates on math and chart interpretation, so happy to discuss this with you. My candidates receive distinctive feedback from interviewers in terms of how they approach numericals and that's because they have the right technique.