Among a sample of diverse coins from an unfamiliar country, each face of any coin portrays one of four things: a judge's head, an explorer's head, a building, or a tree. By examining the coins, a collector determines that none of them have heads on both sides and that all coins in the sample with a judge's head on one side have a tree on the other.

Question: If the statements above are true, which one of the following must be true of the coins in the sample?
Options:
A. All those with an explorer's head on one side have a building on the other.
B. All those with a tree on one side have a judge's head on the other.
C. None of those with a tree on one side have an explorer's head on the other.
D. None of those with a building on one side have a judge's head on the other.
E. None of those with an explorer's head on one side have a building on the other.
Answer: "D"