Concept:A vertical floor arrangement puzzle is solved by testing the possible positions of
P, then fitting the remaining conditions.
Explanation:P lives on an even-numbered floor, but not on floor
4.
So
P can be on floor
2 or floor
6.
Only two people live between
S and
P, so their floors differ by
3.
This gives two starting cases:
Now apply the conditions:
R lives immediately below
T, and
U lives on an even-numbered floor.
These conditions give three possible arrangements:
Now use the condition:
Q does not live on the bottom-most floor.
In Case 1, the only empty floor is floor
1, so
Q would be on the bottom floor; hence Case 1 is invalid.
In Case 2, the only empty floor is also floor
1; hence Case 2 is invalid.
Only Case 3 remains, and
Q is placed on floor
5:
From the final arrangement,
Q is on floor
5 and
S is on floor
3.
Only
U on floor
4 lives between them.
Therefore, exactly one person lives between
Q and
S.
Answer:Option B — One.