In the 1640s Jan Baptista van Helmont planted a small willow in a pot that contained 90.9 kg of soil. After five years, the plant weighed 76.8 kg, but only 0.06 kg of soil had disappeared from the pot. What did van Helmont conclude from this experiment?

A) 80-90% of the tree's mass is the result of C₃ photosynthesis.
B) The increase in the mass of the tree was from the water that he added over the five years.
C) Most of the increase in the mass of the tree was due to the uptake of CO₂.
D) Soil simply provides physical support for the tree without providing any nutrients.
E) The 0.06 kg of soil was mainly nitrogen.