I agree with the need to check the test question's wording. From what you showed us, I am not convinced we are talking about a tap situation at all. What, for example, is the 600 amp thing? A breaker? A feeder? Also, where and how is the 200 amp connection made? Is there an overcurrent device at the point of connection?
Let me add the suggestion that you be wary of a possible trick question. For example, if you are looking for the size of the wire that feeds the 200 amp panel, do you think it matters whether the tap rules apply?