TOEFL Listening: TPO-TOEFL听力TPO - 7QOJFH3K74P2LM7ZR$

According to the professor, what were two purposes of the reed mats? A. To provide a comfortable area for artists to stand on while painting. B. To prevent moisture from damaging frescoes. C. To cover and protect frescoes during the cold season. D. To create a smooth surface for the application of plaster.