PT 5 S1 Q19

A tree's age can be determined by counting the annual growth rings in its ... ...

Which one of the following, if true, contributes most to an explanation of the archaeologists' success in using annual rings to establish the relative ages of the tombs at the Pazyryk site?
(A) The Pazyryk tombs were all robbed during ancient times, but breakage of the tombs' seals allowed the seepage of water, which soon froze permanently, thereby preserving the tombs' remaining artifacts.
(B) ...
(C) ...
(D) ...
(E) ...

*This question is included in Practice Set: "Resolve/Explain" Questions, Set 2 - Difficult/Uncommon Mix (25Q)