Fungi are ecologically important for all of the following EXCEPT:
a. are used as food by a variety of animals (including humans)
b. recycling of chemicals between the biological and physical worlds
c. atmospheric oxygen is a major by-product of fungal phototrophy
d. sources of toxic chemicals, including antibiotics
e. mycorrhizal association with vascular plants

sources of toxic chemicals, including antibiotics

Explanation:

photosynthesis makes the glucose that is used in cellular respiration to make atp. the glucose is then turned back into carbon dioxide, which is used in photosynthesis. while water is broken down to form oxygen during photosynthesis, in cellular respiration oxygen is combined with hydrogen to form water.