Final answer:
The provided information doesn't specify which plant increases sapwood production but gives details on a plant adding oxygen and another with antifungal properties. Plant A is described as adding oxygen, which aligns more with air purification. Without further details on plants C and D, a direct answer on sapwood production isn't possible.
Step-by-step explanation:
It appears that there's a misunderstanding in the question, as it asks about sapwood production in plants related to air purification. However, the provided information doesn't directly link any specific plant to sapwood production but discusses antifungal properties and a substance's ability to remove carbon dioxide gas and add oxygen.
In the context of indoor plants that could help purify the air, Plant A seems to be associated with air purification because it is described as a plant that adds oxygen, thereby allowing better breathing. While Plant D was researched for antifungal properties, this doesn't necessarily mean it's associated with enhanced sapwood production or air purification.
Plant C and Plant D are not specifically described, making it unreasonable to make a connection to sapwood production without additional information. The mention of plants with sealed cuts faring better suggests that sealant may help in protecting the plant from infection or moisture loss, which is beneficial for overall plant health but unrelated to the ability to purify air.