How does the structure of DNA explain chargaff's rule?

Chargaff's rules state that DNA from any species of any organism should have a 1:1 stoichiometric ratio (base pair rule) of pyrimidine and purine bases and, more specifically, that the amount of guanine should be equal to cytosine and the amount of adenine should be equal to thymine

Fungi are not able to ingest their food like we do, nor can they manufacture their own food the way plants do. Instead, fungi feed by absorption of nutrients from the environment around them.Most fungi are saprophytes, feeding on dead or decaying material.