I understand your point. However, the passage has explicitly stated that the lack of access to emergency exits is a cause for these fatalities. Therefore, removing another potential cause doesn't strengthen this argument because we already know that access to emergency exits plays a role.
We are trying to choose an answer choice that would strengthen the solution of removing the seats. Because we have already accepted from the premises that these seats do play a role.
This is why answer choice A, it provides an analogous situation where removing the seats restricting access was helpful in reducing fatalities.
I hope this helps. Please let me know if you have any other questions or would like me to elaborate further.