This is actually something of a trick question, because it’s just a way of re-asking the second question (what you know about the company) and the fourth (what you know about the position). It’s asked because it tells whether people give flippant answers to questions (things like “because I’m a people person”) or whether they think about things and give a genuine question. This is a good question to formulate an answer for in advance – basically, just come up with a few things that seem intriguing to you about the company and the position and reasons why they interest you.