Prolonged and unseasonable frosts produce frost rings in deciduous tre

Prolonged and unseasonable frosts produce frost rings in deciduous trees, which grow in moderate climates. Frost rings do not appear in any of the fossilized deciduous trees that have been found in Antarctica. Hence, it is unlikely that such frosts occurred in Antarctica at the time the fossilized trees lived. Which of the following is an assumption on which the argument depends？

A．There are fossilized nondeciduous trees from Antarctica that bear frost rings.

B．Deciduous trees are more likely to bear frost rings than are other tree varieties.

C．The process of fossilization does not completely obscure frost rings in deciduous trees.

D．Present-day deciduous trees are more sensitive to changes in temperature than were the deciduous trees of ancient Antarctica.

E．Prolonged and unseasonable frosts that might have occurred in Antarctica when the now-fossilized trees were still living did not always produce frost rings in deciduous trees.