There are two scenarios in which all of the Ps are Us.
3 S/F U P 2 F N R 1 F N R
And
3 S/F U P 2 S/F U P 1 F N R
Based on this, there is no reason why we couldn't have an F on floor 3. This would prove why E is wrong. And since floor 1 is N and cannot be production due to this new rule, it must be research. Since no research car is a sports car, it is a family car.
I hope this helps. Please let me know if you have any other questions.